A taxonomic revision of the Thesium goetzeanum species complex (Santalaceae) from Lesotho, South Africa and Swaziland

South African Journal of Botany 119 (2018) 45–62

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A taxonomic revision of the Thesium goetzeanum species complex (Santalaceae) from Lesotho, South Africa and Swaziland N. Visser a,b,⁎, M. Marianne le Roux a,b, B.-E. van Wyk a a b

Department of Botany and Plant Biotechnology, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa Biosystematics Research and Biodiversity Collections Division, Pretoria National Herbarium, South African National Biodiversity Institute, Private Bag X101, Pretoria 0001, South Africa

a r t i c l e

i n f o

Article history: Received 23 October 2017 Received in revised form 24 July 2018 Accepted 1 August 2018 Available online xxxx Edited by JS Boatwright Keywords: Alpha taxonomy Apical beard Identification key New species Tepals Thesium

a b s t r a c t The genus Thesium L. is in urgent need of revision and has been identified as a priority genus for taxonomic research in South Africa. The revision of 16 morphologically similar grassland species from Lesotho, South Africa and Swaziland, here referred to as the T. goetzeanum complex, is a first step towards a comprehensive revision of the genus. All members of the complex share the following characters: (1) tepals with a prominent apical beard, (2) anthers attached to the perianth tube with post-staminal hairs, (3) stigmas usually not sessile (rarely sessile in T. gracilarioides A.W.Hill and T. gypsophiloides A.W.Hill), (4) monotelic inflorescences, (5) leaves, bracts and bracteoles leaf-like, not scale-like, (6) stems leafy, not rush-like, and (7) stems and leaves glabrous. A comprehensive study of morphology, type specimens, distribution information, available literature, as well as field observations, indicate that the number of accepted species should be reduced from 16 to 9, including the newly recognised species T. infundibulare N.Visser and M.M.le Roux sp. nov. The first comprehensive description of T. procerum N.E.Br. is also provided. A taxonomic revision of the T. goetzeanum complex is presented, including an identification key, updated nomenclature and typifications, descriptions, diagnostic characters, distribution maps and conservation notes for all nine recognised species. © 2018 SAAB. Published by Elsevier B.V. All rights reserved.

1. Introduction Thesium L. is a large genus (±350 species) of hemi-parasites that is included in the family Santalaceae (Forest and Manning, 2013; Nickrent and García, 2015; The Angiosperm Phylogeny Group, 2016). The majority of Thesium species are concentrated in southern Africa (±180 species), with the remainder occurring in tropical and northern Africa, Europe, Asia and South America (Germishuizen et al., 2006; Forest and Manning, 2013; Nickrent and García, 2015). Thesium (including Kunkeliella W.T.Stearn and Thesidium Sond.) is monophyletic and sister to Osyridicarpos A.DC. plus Lacomucinaea Nickrent & M.A. García (Der and Nickrent, 2008; Forest and Manning, 2013; Nickrent and García, 2015). The genus comprises hemi-parasitic herbs or shrubs with sessile, linear or scale-like leaves and dry, nut-like fruits (De Candolle, 1857a; Hill, 1915). Thesium was first described by Linnaeus (1753) and included four species. Later, both De Candolle (1857a, 1857b) and Sonder (1857a) simultaneously, but independently, published reviews on Thesium. These publications resulted in many inconsistencies and contradictions in species concepts and classification systems. Sonder (1857b) later ⁎ Corresponding author at: Department of Botany and Plant Biotechnology, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa. E-mail address: [email protected] (N. Visser).

https://doi.org/10.1016/j.sajb.2018.08.005 0254-6299/© 2018 SAAB. Published by Elsevier B.V. All rights reserved.

published an amendment in an attempt to reconcile some of the conflicting taxonomic information. Hill (1915, 1925) conducted a comprehensive taxonomic study of the southern African species, which also included descriptions of several new species. Hill's circumscription of species were mostly congruent with those of De Candolle (1857a) and Sonder (1857b), although his classification system differed from theirs mostly due to his narrower perception of morphological variation resulting from the limited geographic range of his study (Moore et al., 2010). Molecular studies show that the sections described by Hill are polyphyletic (Moore et al., 2010; Nickrent and García, 2015). Both these studies focussed predominantly on Fynbos species of Thesium and therefore little is known about the relationships among other species. It is, however, clear that Fynbos and grassland species form two monophyletic sister clades (Moore et al., 2010; Nickrent and García, 2015). Since the work of Hill, 38 new southern African Thesium species have been described (e.g., Brown 1932; Brenan 1979), yet no attempt has been made to amalgamate and evaluate all of the available taxonomic information for the genus. Currently no complete identification key exists, and considerable confusion remains surrounding species concepts and identification. Thesium has consequently been identified as a high priority for taxonomic research in South Africa and is in urgent need of a revision (Victor et al., 2015). Working towards a comprehensive taxonomic revision of the genus, we review a group of 16 morphologically similar grassland species from

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Lesotho, South Africa and Swaziland (see Table 1) referred to here as the T. goetzeanum complex. The T. goetzeanum complex forms part of section Barbata A.W.Hill as delineated by Hill (1925), corresponding to the section Frisea Rchb. in the classification systems of De Candolle (1857a) and Pilger (1935) or subgenus Frisea (Rchb.) Peterm. of Hendrych (1972). Species in the T. goetzeanum complex are distinguished by the following characters: (1) tepals with a prominent apical beard, (2) anthers attached to the perianth tube with post-staminal hairs, (3) stigmas usually not sessile (occasionally sessile in T. gracilarioides A.W.Hill and T. gypsophiloides A.W.Hill), (4) monotelic inflorescences, (5) leaves, bracts and bracteoles leaf-like, not scalelike, (6) stems leafy, not rush-like, and (7) stems and leaves glabrous (Fig. 1A–D). The T. goetzeanum complex includes some of the most taxonomically problematic species in the genus. The distinctions among species have been blurred by the increased levels of variation now evident from more recent collections, rendering their identification difficult or impossible. This intraspecific variation was not evident to Hill (1915, 1925) and Brown (1932) from the limited material available to them, on which they based their species concepts (Hendrych, 1972; Moore et al., 2010). The difficulties in identifying species are highlighted by the fact that four species in the T. goetzeanum complex are currently classified as data deficient due to taxonomic reasons (T. coriarium A. W.Hill, T. junodii A.W.Hill, T. mossii N.E.Br. and T. vahrmeijeri Brenan) (Raimondo et al., 2009). We recognise nine species in the present treatment, reducing seven names to synonymy (see Table 1) as the diagnostic characters on which these taxa were based fall within the range of variation of previously described species. We provide the first comprehensive description of T. procerum N.E.Br., which was only briefly described by Brown (1932), and describe one new species, T. infundibulare N.Visser and M.M.le Roux.

studied in the field. Three plants from each population were collected where possible. Specimens collected were deposited in PRE. Species distributions were determined from locality information supplied on specimen labels and specimens collected during fieldwork. The SANBI gazetteer v. 4 compiled and managed by Powrie (2015) was used to confirm collection localities. Final distribution maps were compiled using ArcMap v. 10.3.1 (ESRI, Inc.). Specimens are cited following the quarter degree grid reference system of Leistner and Morris (1976). Vegetative and reproductive morphological characters, as well as distribution information, were used to sort specimens into 10 operational taxonomic units (OTU's), which were finally coalesced into 9 species. Three specimens representing the widest range of variation were selected from each OTU, and three measurements taken of each character on each specimen. Floral measurements were taken using ZEN lite software v. 2.0 (Carl Zeiss Microscopy GmbH), to ensure accuracy of measurements below 3 mm. Around 200 flowers were rehydrated for five minutes in “Windolene” (cleaning agent), after which floral dissections were made using a Nikon SMZ 745 T stereo microscope (Nikon Corporation). Photos of vegetative parts, floral parts (including flower cross sections), and fruits were taken using a Zeiss Discovery V8 Stereo microscope, with a Zeiss 60 N–C, 2/3″, 0.63× camera attached and Zeiss ZEN software (Carl Zeiss Microscopy GmbH). Photographs and figure plates were edited using Microsoft Publisher software v. 14.0.7181.5 (Microsoft Corporation). Suggested conservation statuses are provided according to the guidelines given by the International Union for Conservation of Nature (IUCN Standards and Petitions Subcommittee, 2017) and evaluated in collaboration with Ms. Lize von Staden (South African Threatened Species Program, South African National Biodiversity Institute). 3. Results and discussion

2. Materials and methods 3.1. Diagnostically reliable characters Morphological characters of ±430 herbarium specimens of Thesium were examined from the collections in BM, BNRH, BOL, J, K, NBG (including SAM), NH, PCE, PRE and PRU. In addition, digital images of type specimens from B, BR, EM, MO, S and W were examined via JSTOR Global Plants (https://plants.jstor.org). Details of these images and specimens studied are provided in the treatment of each species. Fieldwork was conducted at various sites across the Gauteng, Free State, Limpopo, Mpumalanga and KwaZulu-Natal provinces of South Africa between October 2016 and December 2017 in the flowering period of the grassland species of Thesium (August–February). Plants were observed and photographed in their natural habitat to record information such as habit, colour of vegetative and reproductive parts, and possible pollinators. Six of the nine species recognised and treated here were

A combination of nine characters was used to distinguish among species of the T. goetzeanum complex. Hill (1925) previously utilised habit, fusion of bracts to pedicels/peduncles, and inflorescence type as diagnostic characters. In addition to these, five more diagnostic characters are newly recognised here: perennial vs annual life history, rootstock, presence or absence of vegetative scales, placental column structure, and the presence or absence of fruit stipes. A summary of diagnostic characters is provided in Table 2. 3.1.1. Vegetative morphology The growth form of species in the T. goetzeanum complex is extremely variable (Hill, 1915). Factors such as elevation, fire, grazing,

Table 1 A list of all accepted species in the Thesium goetzeanum complex with synonyms. Heterotypic and homotypic synonyms are denoted with = and ≡ respectively. References listed next to previous synonyms refer to the publications where each synonym was instated. Accepted species

New synonyms

Previous synonyms

1. T. goetzeanum Engl.

= T. coriarium A.W.Hill = T. deceptum N.E.Br = T. macrogyne A.W.Hill = T. nigrum A.W.Hill = T. orientale A.W.Hill

= T. caespitosum Robyns & Lawalrée (Hilliard, 2006) = T. rhodesiacum Pilg. (Hilliard, 2006) = T. rogersii A.W.Hill (Hilliard, 2006) = T. schweinfurthii var. laxum Engl. (Baker and Hill, 1911)

2. T. gracilarioides A.W.Hill 3. T. gracile A.W.Hill 4. T. gypsophiloides A.W.Hill 5. T. infundibulare N.Visser & M.M.le Roux 6. T. lobelioides A.DC. 7. T. procerum N.E.Br. 8. T. resedoides A.W.Hill

9. T. vahrmeijeri Brenan

= T. palliolatum A.W.Hill (Brown, 1932)

≡ T. recurvifolium Sond. (Hill, 1925) = T. junodii A.W.Hill = T. mossii N.E.Br

= T. burkei A.W.Hill (Brown, 1932) = T. dumale N.E.Br (Hilliard, 2006) ≡ T. welwitschii sensu Baum non Hiern., name superfluous (Hill, 1910)

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Fig. 1. Morphological features within the Thesium goetzeanum complex showing seven diagnostic characters for the complex (A–D), rootstock characters (E–I) and important fruit characters (J–K). A. Cross-section of a typical flower showing the: (1) prominent apical beard, (2) post-staminal trichomes, and (3) non-sessile stigma (T. goetzeanum). B. (4) Monotelic inflorescence with (5) leaf-like bracts (T. goetzeanum). C. (6) Leafy stems, not rush-like (T. gracilarioides). D. (7) Glabrous stems and leaves (T. procerum). E. Perennial, thick, woody rhizome (T. gracilarioides). F. Annual slender tap root (T. vahrmeijeri). G. Belowground woody rhizome with a network of lateral stems (T. goetzeanum). H. Perennial, branched, non-rhizomatous rootstock (T. gypsophiloides). I. Vegetative scales on the woody rhizome and lower parts of the stems (T. goetzeanum). J. Fruit stipe present (T. procerum). K. Fruit stipe absent (T. gracilarioides). The scale bars represent 1 mm.

Table 2 A summary of the nine species of the Thesium goetzeanum complex and the main diagnostic characters used to distinguish among them. Characters and character states are presented as follows: (1) habit: herb (−), shrub (+), suffrutex (++); (2) growth form: more or less erect (−), spreading (+), virgate (++); (3) life history: annual (−), perennial (+); (4) rootstock: non-woody branched (−), rhizome (+), woody branched (++); (5) vegetative scales: absent (−), present (+); (6) inflorescence type: compound and simple dichasia (−), compound monochasia (+), racemose cyme (++); (7) bract fusion to pedicel/peduncle: less than 1/4 (−), about 1/2 (+), more than 2/3 or fully (++); (8) placental column structure: straight (−), twisted (+); (9) fruit stipe: absent (−), present (+). Missing data are indicated with a “?“.

(1) Habit (2) Growth form (3) Life history (4) Rootstock (5) Vegetative scales (6) Inflorescence type (7) Bract fusion to pedicel/peduncle (8) Placental column (9) Fruit stipe

T. goetzeanum

T. gracilarioides

T. gracile

T. gypsophiloides

T. infundibulare

T. lobelioides

T. procerum

T. resedoides

T. vahrmeijeri

++ ++ + + + ++ ++ − −

++ − (+) + + + ++ ++ − −

++ − + + + − − − −

+ − + ++ − + (−) + − −

++ − + ? + ++ ++ − +

++ − + ? ? ++ ++ − −

+ + + + + ++ ++ + +

++ − + + + ++ ++ − −

− − (+) − − − ++ ++ − +

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habitat and host-species all contribute to this infra-specific variation (Cohn, 2004; Luo et al., 2012; Gamoun, 2014). Species in the T. goetzeanum complex are usually suffrutices, with only the lower parts of the stems woody, except T. vahrmeijeri which is entirely herbaceous, and T. procerum and T. gypsophiloides which are shrubs with larger plants having woody stems. The second year of growth often differs markedly from that of the first year. Some characters states of the habit are consistent. Species in the T. goetzeanum complex are generally erect or suberect and branched, although Thesium gracilarioides, T. gracile and T. vahrmeijeri may occasionally be spreading or decumbent, while T. procerum is usually spreading and T. goetzeanum virgate. Thesium procerum and T. gypsophiloides can grow as tall as 1.5 and 2.0 m, respectively, but the other species reach an average height of 0.3 m, never exceeding 1.0 m. Examples of the habit of each species are shown in Fig. 5. The majority of species in the T. goetzeanum complex are perennials with thick woody rhizomes (Fig. 1E), with the exception of T. vahrmeijeri, which is an annual with a slender, non-woody, branched root system (Fig. 1F) and T. gypsophiloides which is a perennial with a woody, branched root system (Fig. 1H). The rootstocks of T. infundibulare and T. lobelioides remain unknown as we have not studied them in the field and the rootstocks are neither present on herbarium sheets, nor have they been mentioned in the literature. Vegetative scales (Fig. 1I) and lateral belowground stems (Fig. 1G) are both associated with perennial species with woody rhizomes. Vegetative scales

occur on the rhizome and the lower parts of the stems, and these nodes are likely growth points for both vertical above-ground- and lateral below-ground stems (Hilliard, 2006). Conversely, vegetative scales and lateral belowground stems are absent from T. gypsophiloides and T. vahrmeijeri, both of which have solitary vertical stems. Older plants of T. procerum sometimes have solitary vertical stems but are distinguished from T. gypsophiloides and T. vahrmeijeri by the presence of vegetative scales. 3.1.2. Reproductive morphology The structure of the inflorescence is very important in distinguishing among species of the T. goetzeanum complex but is also the most challenging to understand. This can be attributed to the morphological similarity of the leaves and the bracts, and it is generally impossible to distinguish between them. For example, Hilliard (2006) reports that the leaves grade into the bracts in T. goetzeanum, T. gracile and T. resedoides. We define leaves as structures not associated with floral parts, and bracts as structures closely associated with floral parts. On this basis, we recognise several inflorescence types in the T. goetzeanum complex, all of which are monotelic (Fig. 2). Thesium gracile has a combination of simple and compound dichasial cymes with occasional monochasial cymes (Fig. 2D), and T. gypsophiloides has compound dichasial and monochasial cymes which resemble scorpioid cymes (Fig. 2E). The remaining species (T. goetzeanum, T. gracilarioides, T. infundibulare, T. lobelioides, T. procerum, T. resedoides and T. vahrmeijeri)

Fig. 2. Inflorescence types within the Thesium goetzeanum complex. (A–C) Monotelic, racemose inflorescences, which might occur in combinations of types A–C within a single plant (T. goetzeanum, T. gracilarioides, T. infundibulare, T. lobelioides, T. procerum, T. resedoides, T. vahrmeijeri). A. Monotelic racemose inflorescence with a terminal dichasial cyme. B. Monotelic racemose inflorescence with randomly placed monochasial cymes. C. Monotelic racemose inflorescence with randomly placed dichasial cymes with bracts often only partially fused. D. Simple or compound dichasial and monochasial cymes (T. gracile). E. Compound monochasial, and occasionally simple dichasial cymes, with peduncles tending towards the arrangement of scorpioid cymes (T. gypsophiloides).

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all have similar racemose cymes interspersed with simple dichasial (Fig. 2A, C) and monochasial cymes (Fig. 2B). In T. gracile the bracts are clearly fused to prominently long secondary peduncles for up to a quarter of the length of the peduncles (Fig. 2D; Fig. 6B2), while in T. gypsophiloides the bracts are fused to the peduncles for up to half the length of the peduncles (Fig. 2E). In the remainder of species, the bracts are completely fused to the entire peduncle or rarely only two thirds of its length. The ovaries of species in the T. goetzeanum complex are always inferior and unilocular, with a central free placental column (Hendrych, 1972) bearing three ovules. We determined that all species in the T. goetzeanum complex have straight placental columns (Fig. 3A), except in T. procerum that has twisted placental columns (Fig. 3B). The nature of the placental columns and ovules has previously been found to be a consistent character to differentiate between species. For example, the Eurasian species T. alpinum L. and T. wightianum Wall. both have twisted placental columns bearing three unitegmic ovules (Bhatnagar and Agarwal, 1961). An in-depth study of ovarian characters of the T. goetzeanum complex and related grassland species should be conducted in the future, as this might elucidate more information about species relationships. An important diagnostic character that has been overlooked previously in species of the T. goetzeanum complex is the presence or absence of a fruit stipe. Stipitate fruits have been recorded for several Thesium species occurring in the Flora Zambesiaca area (Hilliard, 2006) but never for species in the T. goetzeanum complex. Here, three species (T. procerum, T. vahrmeijeri and T. infundibulare) have been observed to have stipitate fruits (Fig. 1J), while the remaining species (T. goetzeanum, T. gracilarioides, T. gracile, T. gypsophiloides, T. lobelioides and T. resedoides) have sessile fruits (Fig. 1K). Combinations of the above-mentioned characters were used for the present species delimitations. 3.2. Diagnostically unreliable characters Several distinguishing characters used in the last comprehensive revision by Hill (1925) were not diagnostically informative for the T. goetzeanum complex. This is due to infraspecific variation that was not previously understood, which often makes assigning a specimen to a species almost impossible (Hill, 1915). Hill (1925) used the length of bracts and bracteoles in relation to mature flowers (shorter, equal or longer than the flower) to distinguish species, and Hendrych (1972) also regarded this as an important diagnostic character for Eurasian and North-African Thesium species. However, for species in the T. goetzeanum complex, all three these character states have been observed in different populations of the

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same species, in the same area, and occasionally within a single plant. Consequently, bract and bracteole length in relation to flower length is an ambiguous character for species of the T. goetzeanum complex and possibly also for the majority of the southern African grassland species. In members of T. goetzeanum complex the length of the style and the position of the stigma in relation to the anthers (below, in the middle or above) vary considerably among populations. Hill (1915) observed this variation and suggested heterostyly as a possible explanation. Another distinguishing character used by Hill (1925) is the presence or absence of external perianth “glands”. However, Hill (1915) himself noted the “doubtful significance” of this character. A continuous range of intraspecific variation was observed in the T. goetzeanum complex, from “glands” that are barely visible to those that were very prominent, rather than the binary character states (absence or presence of “glands”) proposed by Hill. The nature and purpose of these “glands” remains uncertain (Hill, 1915). No visible secretions were observed by the authors in the present study. Hendrych (1972) also made no mention of external “glands” in his detailed study of the natural history and systematics of the genus Thesium. Lastly, contrary to the observation made by Hendrych (1972), the degree of reticulation on the fruits varies within species of the T. goetzeanum complex. Species in the T. goetzeanum complex generally show clear reticulation, except in T. infundibulare, where the reticulation is faint or absent.

3.3. Geographical distribution The geographical distribution of species is informative in the T. goetzeanum complex, as several species are local endemics. Most notably, T. vahrmeijeri is found only on the northern KwaZulu-Natal- and southern Mozambique coast, T. gypsophiloides is restricted to KwaZulu-Natal, T. lobelioides occurs in the Eastern Cape and Free State, allopatric from the other species in this complex, and T. infundibulare is found mainly in Swaziland. Although T. resedoides and T. goetzeanum are both widespread species, T. resedoides is confined to the savanna biome (Northern Cape, North West, Limpopo, Mpumalanga and Swaziland), while T. goetzeanum is confined to the grassland biome (North West, Limpopo, Mpumalanga, Gauteng, KwaZulu-Natal and the Eastern Cape) (Fig. 4). Altitude above sea level is also a good supplementary measure to distinguish between species. For example, T. gracilarioides has only been collected at elevations above 1600 m above sea level (a.s.l.) whereas the sympatric species T. gracile and T. resedoides have only been collected at elevations below 1600 m a.s.l. Thesium vahrmeijeri is strictly coastal, found up to a maximum elevation of 152 m a.s.l.

Fig. 3. Two configurations of placental columns found in the Thesium goetzeanum complex. A. Straight placental column (T. goetzeanum, T. gracilarioides, T. gracile, T. gypsophiloides, T. infundibulare, T. lobelioides, T. resedoides, T. vahrmeijeri). B. Twisted placental column (T. procerum).

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Fig. 4. The distribution patterns of Thesium goetzeanum and T. resedoides showing association with biome types. Thesium goetzeanum is confined to the grassland biome, including grassland biome patches imbedded within the savanna biome, while T. resedoides is confined to the savanna biome.

4. Key to the species in the Thesium goetzeanum complex Species of the T. goetzeanum complex share the following characters: (1) glabrous stems and leaves, (2) uni-nerved and decurrent leaves, (3) leaf-like bracts and bracteoles, (4) campanulate flowers, (5) reduced floral discs, (6) post-staminal hairs present and attaching anthers to perianth, and (7) ellipsoid, prominently 10-ribbed fruits. 1a. Inflorescences cymose, invariably with dichasia or monochasia, usually compound or occasionally simple; bracts fused halfway up the peduncle or less: 2a. Cymes compound dichasia or rarely with simple monochasia; bracts fused to between 1/8 and 1/4 of peduncle; stamens inserted on tepals; fruit sessile .................................................................................. 3. T. gracile 2b. Cymes compound monochasia, tending to resemble scorpioid cymes; bracts fused to ±1/2 of peduncle; stamens inserted in perianth tube; fruit shortly stipitate (0.2–0.5 mm) ................... 4. T. gypsophiloides 1b. Inflorescences racemose, simple and accompanied by occasional dichasia or monochasia; bracts fused to 2/3 or more of peduncle, very rarely fused to ±1/3 of peduncle in cymes: 3a. Plants densely leafy (14 to 40 leaves per 50 mm at middle of stem); stamens inserted in perianth tube; style < 0.4 mm or stigma subsessile ..................................................................................... 2. T. gracilarioides 3b. Plants sparsely to moderately leafy (5 to 18 leaves per 50 mm at middle of stem); stamens inserted on tepals; style >0.4 mm: 4a. Fruit stipitate; flowers with elongated receptacle: 5a. Herbaceous annuals; rootstock a slender, non-woody branched rootstock; vegetative scales absent on roots and lower parts of stems .............................................................................................9. T. vahrmeijeri 5b. Suffrutescent perennials or shrubs; rootstock a woody rhizome; vegetative scales present on roots and lower parts of stems: 6a. Shrubs, up to 1.5 m tall; stems terete; placental column twisted ................................................................................................. 7. T. procerum 6b. Suffrutices, up to 0.3 m tall; stems sulcate; placental column straight.......................................................................................... 5. T. infundibulare

4b. Fruit sessile; flowers without elongated receptacle: 7a. Flowers <3 mm; leaf apex cartilaginous; style usually <1 mm, never longer than 1.1 mm; stems much-branched.......... 8. T. resedoides 7b. Flowers > 3 mm; leaf apex not cartilaginous; style usually >1 mm, never shorter than 0.8 mm; stems sparingly branched: 8a. Plant green or occasionally green-glaucous in colour; tepals triangular or narrowly triangular, 1.1–1.5(−1.7) mm long .................................................................................................. 1. T. goetzeanum 8b. Plant mauve or greyish in colour; tepals linear, 1.3–2.2 mm long ....................................................................................................... 6. T. lobelioides 5. Taxonomic treatment 1. T. goetzeanum Engl. in Bot. Jahrb. Syst. 30: 306 (1902); Baker and A.W.Hill in Dyer, Fl. Trop. Afr. 6(1): 418 (1911); A.W.Hill in Dyer, Fl. Cap. 5(2): 181 (1925); N.E.Br in Burtt Davy, Man. Pl. Transvaal 2: 459 (1932); Retief and P.P.J.Herman in Plants of the northern provinces of South Africa: 597 (1997); Polhill in Beentje, Fl. Trop. E. Africa., Santal.: 20 (2005); Hilliard in Fl. Zambes. 9(3): 236 (2006); Retief and N.L.Mey. In Plants of the Free State: 749 (2017). Type: Tanzania, Mbeya District (0833): Unyika, Fingano (–CD), 26 Oct 1899, Goetze 1379 (B, holo. – image!; BM!, K!, iso). T. schweinfurthii var. laxum Engl. in Pflanzenw. Ost-Afrikas: 168 (1895). Type: Tanzania (0337): Unterhalb [below] Marangu (–BC), Volk 2100 (Type not located, possibly in B and destroyed in World War II). T. rogersii A.W.Hill in Bull. Misc. Inform. Kew 1913: 78 (1913); Baker and A.W.Hill in Dyer, Fl. Trop. Afr. 6(1): 1059 (1913); N.E.Br. in Burtt Davy, Man. Pl. Transvaal 2: 460 (1932). Type: Zimbabwe, Victoria Falls (1725): Kandahar Island (−DD), 11 Oct 1911, Rogers 5467 (K [2 sheets], holo.!; BM!, iso.). T. coriarium A.W.Hill in Bull. Misc. Inform. Kew 1: 24 (1915), syn. nov.; A.W.Hill in Dyer, Fl. Cap. 5(2): 182 (1925); Retief and P.P.J.Herman in Plants of the northern provinces of South Africa:

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597 (1997). Type: South Africa, Free State, Harrismith (2829): Orange River Colony, Harrismith (–AC), Nov 1904, Sankey 223 (K, holo.!; PRE!, iso.). T. macrogyne A.W.Hill in Bull. Misc. Inform. Kew 1: 34 (1915), syn. nov.; A.W.Hill in Dyer, Fl. Cap. 5(2): 180 (1925); Retief and N.L.Mey. in Plants of the Free State: 751 (2017). Type: South Africa, Free State, Bethlehem (2828): Bethlehem, Orange River Colony (–AB), Richardson s.n. (K, holo.!; PRE!, iso.). T. nigrum A.W.Hill in Bull. Misc. Inform. Kew 1: 35 (1915), syn. nov.; A.W.Hill in Dyer, Fl. Cap. 5(2): 183 (1925); Retief and P.P.J.Herman in Plants of the northern provinces of South Africa: 598 (1997). Type: South Africa, precise locality unknown, possibly Free State, 1862, Cooper 826 (K, lecto.!, designated here). Other original material: South Africa, KwaZulu-Natal, Underberg (2929): Giant's Castle (–BC), Guthrie 4954 (K, syn.!). Pietermaritzburg (2930): between Pietermaritzburg and Greytown (–BC), Nov 1883, Wilms 2253 (K, syn.!). Kokstad (3029): East Griqualand, near Kokstad (–CB), Oct 1883, Tyson 1863 (BOL, syn.!; K, syn.!; SAM, syn.!). Precise locality unknown, possibly Free State province, 1862, Cooper 1061 (K, syn. [2 sheets]!; W, syn. – image!). [Note: Cooper 826 (K) was chosen as the lectotype of T. nigrum, from several available syntypes, as the specimen is named and annotated by A.W.Hill and, unlike the other syntypes, it is rich in reproductive material]. T. orientale A.W.Hill in Bull. Misc. Inform. Kew 1: 36 (1915), syn. nov.; A.W.Hill in Dyer, Fl. Cap. 5(2): 180 (1925). Type: South Africa, KwaZulu-Natal, Kokstad (3029): East Griqualand, near Kokstad (–CB), 1882, Tyson 3157 (K, lecto.!, designated here; PRE!, isolecto.). Other original material: South Africa, Eastern Cape, Umtata (3128): Tembuland, Tabase, near Baziya (–CB), Baur 336 (K, syn.!; SAM, syn.!). Fort Beaufort (3226): Stockenstrom Division, Katberg (–CB), Hutton s.n. (K, syn.!; S, syn. – image!). Lesotho (Basutoland), precise locality unknown, Cooper 3094 (K, syn.!). [Note: Form several syntypes, Tyson 3157 (K) was chosen as the lectotype of T. orientale as the specimen is named and annotated by A.W.Hill, and a duplicate is housed in PRE]. T. rhodesiacum Pilg., sensu Eyles in Trans. Roy. Soc. South Africa 5: 344 (1916), nom. nud. T. deceptum N.E.Br. in Burtt Davy, Man. Pl. Transvaal 2: 460 (1932), syn. nov.; Retief and P.P.J.Herman in Plants of the northern provinces of South Africa: 597 (1997). Type: South Africa, Gauteng, Pretoria (2528): Premier Mine (–DA), Sep 1915, Rogers 14,780 (K, holo.!; PRE!, iso.). T. caespitosum Robyns and Lawalrée in Bull. Jard. Bot. État Bruxelles 31: 512 (1961). Type: Ruanda [Rwanda], Territoire Kibungu [Kibungu Territory] (0130): Parc National de la Kagera, colline Ndama [Kagera National Park, Ndama Hill] (–AD), 27 Feb 1958, Troupin 6165 (BR – image, holo.!; K!, iso.). Rhizomatous suffrutex, 0.1–0.5(0.8) m tall, vegetative scales present on rhizome and lower parts of aerial stems, stems 1 to 22(47), arising from rhizome at intervals, erect or suberect, virgate, often with vegetative shoots overtopping inflorescences, simple or occasionally branched, green, sulcate, moderately leafy (4 to 16 leaves per 50 mm at middle of stem). Leaves adpressed or slightly spreading, linear or narrowly obovate, 4.5–20.0 × 0.3–1.8 mm, apex acute or pungent and usually not cartilaginous, midrib raised on both surfaces, margins entire. Flowers usually solitary in bract axils, sometimes with simple 3-flowered dichasial cymes, or very rarely compound dichasial cymes, arranged in 4 to 13(19)-flowered monotelic racemose inflorescences, often terminating in simple dichasial cymes; cyme peduncles 0.5–6.0(10.5) mm long, pedicels 0–3(5) mm long. Bracts linear-lanceolate, 4.0–12.5 × 0.4–1.8 mm, usually acuminate, margins entire or occasionally scabrous, fused to entire pedicel or in cymes fused to about 1/3 of cyme peduncles; bracteoles 2.0–6.0 × 0.2–0.9 mm. Perianth 3.0–4.5 mm long, elongate receptacle absent, “glands” often visible on outside; lobes narrowly triangular, 1.1–1.7 × 0.3–0.6 mm, apex hooded, with dense apical

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beard. Stamens inserted at base of tepals; filaments 0.3–0.4 mm long; anthers 0.4–0.7 mm long. Style 0.8–1.2 mm long, stigma ± opposite anthers. Placental column straight. Fruit sessile, 4.5–7.0 mm long including persistent perianth (2.5–4.5 mm long excluding perianth), 1.5–2.8 mm wide, with faint reticulate venation. Distribution and ecology Thesium goetzeanum is widespread throughout the eastern parts of central and southern Africa, from Kenya, Rwanda, Tanzania, Malawi, Zambia, Mozambique, Zimbabwe, Botswana, Lesotho to South Africa (Polhill, 2005; Hilliard, 2006), where it ranges from the Limpopo and North West provinces south-eastwards through Mpumalanga, Gauteng and Free State to KwaZulu-Natal and Eastern Cape (Figs. 4, 7A). This species occurs mainly in rocky or stony grassland but is also recorded in grassy savanna, at elevations between 1000 and 3000 m a.s.l. The number of plants are more abundant in recently burnt areas. Flowering time is between August and February. Diagnostic characters Thesium goetzeanum is most commonly confused with T. resedoides, likely due to the polymorphic growth forms of both these species but can be distinguished from it by the sparsely branched, parallel stems (Fig. 5A), the presence of vegetative shoots (Fig. 5A1) overtopping the inflorescences (Fig. 5A2), and larger flowers 3.0–4.5 mm long. Thesium resedoides is characterised by much-branched stems that are inclined at ±45° (Fig. 5D), the absence of vegetative shoots overtopping inflorescences, and smaller flowers 2.5–3.3 mm long. The two species are also largely ecologically separated, with T. goetzeanum, occurring in grasslands at elevations up to 3000 m a.s.l., while T. resedoides occurs in savanna below 1700 m a.s.l. Thesium goetzeanum is polymorphic in its growth form, and plants are entirely herbaceous and virgate the first year after fire, while older plants become increasingly woody and often decumbent. Plants occurring on the Drankensberg between Underberg in KwaZulu-Natal and Lydenburg in Mpumalanga tend to be smaller with a slender habit, vegetative shoots overtopping inflorescences, and with adpressed leaves and bracts. The flowers are slightly smaller (3.0–4.0 mm long) and more closed at the apex. Plants occurring elsewhere tend to be more robust in habit, with spreading leaves and bracts, and slightly larger flowers (3.5–4.5 mm long) more open at the apex. In terms of synonymy, when describing T. coriarium, Hill (1915) distinguished the species based on its leathery leaves and bracts, ellipticlanceolate bracts and flower size (4 mm long). However, from the type it is not obvious that either the leaf texture or the bract shape differs significantly from that of T. goetzeanum. Furthermore, the flower size of T. coriarium falls within the range of variation observed in T. goetzeanum (3.0–4.5 mm long). In his key, Hill (1915) suggested that the tepals of T. coriarium are not hooded, however, on the type tepals appear to be hooded as in T. goetzeanum. In the absence of other distinguishing characters T. coriarium and T. goetzeanum cannot be separated. Thesium deceptum was described by Brown (1932) based on its linear-lanceolate bracts with scabrous edges. Thesium goetzeanum is known to have predominantly linear-lanceolate bracts and specimens with scabrous margins are routinely observed. Specimens previously segregated as T. deceptum often dry pinkish but differ from T. goetzeanum in no other way. Thesium macrogyne was diagnosed by Hill (1915) based on its simple racemose inflorescences, very minutely serrulate bract margins, “speciosis” flowers (translated as “showy” flowers) and stigma reaching above the anthers. Thesium macrogyne does not differ from T. goetzeanum in inflorescence type, and the polymorphic bract margins of T. goetzeanum (entire to scabrous) are also not dissimilar to the

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Fig. 5. Habits of the nine species in the Thesium goetzeanum complex. A. T. goetzeanum: (1) vegetative shoots overtopping (2) the highest inflorescences. B. T. gracilarioides. C. T. gracile. D. T. resedoides. E. T. vahrmeijeri: slender non-woody branched rootstock (annual species). F. T. lobelioides. G. T. procerum: thick woody stems op to 40 mm wide. H. T. infundibulare: (1) branching in the upper 2/3 of the stem, (2) large leaves on the lower 2/3 of the stems and (3) vegetative shoots overtopping the highest inflorescences. I. T. gypsophiloides (I photographed by D. Nickrent).

margins observed on the type of T. macrogyne. The term “showy” is considered ambiguous and do not appear to differ from those of T. goetzeanum. Finally, the stigma position of T. macrogyne falls within the variation observed in T. goetzeanum (below- to above the anthers as discussed earlier). Hill (1915) suggested that T. macrogyne does not have external perianth “glands”, however, “glands” can be observed on the type (see discussion on “glands” later). There are therefore no reliable diagnostic characters to distinguish these two species from one another.

Similar to T. coriarium, Hill (1915) diagnosed T. nigrum on its acute, lanceolate bracts, flower size (3 mm long) and conspicuously hooded tepals. Thesium goetzeanum has linear to lanceolate bracts with acute to acuminate apices, flower lengths between 3.0 and 4.5 mm, and clearly hooded tepals. The diagnostic characters of T. nigrum therefore either fall within the observed variation of T. goetzeanum or in the case of the tepals, are similar. Hill (1915) separated T. orientale on its scabrous bract margins and large flower size (4 mm long). As mentioned above, the bract margins

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of T. goetzeanum are polymorphic and range from entire to scabrous. Furthermore, flower size varies within T. goetzeanum (3.0–4.5 mm in length). There are no other differences to distinguish these two species. Finally, Hill (1915) also distinguished T. coriarium, T. macrogyne, T. nigrum and T. orientale from other related species based on the prominence of their external perianth “glands” (more or less conspicuous in all four species). However, this character is known to vary in T. goetzeanum from seemingly being absent to present and very prominent (as discussed earlier) and can therefore not be used to separate species. Thesium coriarium, T. deceptum, T. macrogyne, T. nigrum and T. orientale all occur within the distribution range of T. goetzeanum. Conservation status Thesium goetzeanum is abundant and widespread and is therefore appropriately classified as Least Concern (IUCN Standards and Petitions Subcommittee, 2017). The taxon T. coriarium A.W.Hill, currently listed as data deficient due to taxonomic problems (Raimondo et al., 2009), is now treated as a synonym of T. goetzeanum. Additional specimens examined South Africa. LIMPOPO: 2427 (Thabazimbi): Kransberg, Bergfontein 277 KQ (–BC), 16 Dec 1986, Raal 1188 (PRE); Waterberg, Bergkrans, Bergfontein farm 277 KQ (–BC), 28 Nov 1984, Jacobsen 3460 (PRE). 2428 (Nylstroom): ± 18 km vanaf [from] Nylstroom [Modimolle] (– CB), 04 Nov 1985, Pienaar, 637 (PRE). 2429 (Zebediela): 24 km from Potgietersrus on road to Pietersburg (−AA), 05 Nov 1985, Germishuizen 3389 (PRE). NORTH WEST: 2526 (Zeerust): Swartruggens (−DA), 03 Dec 1938, Sutton 1211 (PRE). 2626 (Klerksdorp): White's Quarry (−AA), 04 Feb 1970, Morris 1038 (PRE). GAUTENG: 2528 (Pretoria): E of Government House (–CA), 07 Sep 1932, Cronje 2 (PRE); Pretoria (–CA), Goosens s.n. (PRE), Moss 79 (PRE); the Hollows near Pretoria (–CA), Nov 1904, Burtt Davy 2535 (BOL); Wonderboom Neck, Magaliesberg (–CA), 05 Oct 1963, Stauffer and Mauve 5249 (PRE); Brummeria (–CB), 10 Nov 1974, Drijfhout 748 (PRE); 01 Dec 1967, Müller 126 (PRE); Koedoespoort near Pretoria (– CB), 21 Sep 1914, Mogg s.n. (PRE); National Botanical Garden, Pretoria, on eastern side of road in grassland area (–CB), 18 Oct 2016, Le Roux 181A (PRE); Pretoria University Farm, near wireless masts (–CB), 05 Nov 1946, Codd 2129 (PRE); Donkerhoek, ± 20 km from National Botanical Garden, on N4 E (–CD), 26 Oct 2016, Visser and Le Roux 205, 206 (PRE); Rietvlei Nature Reserve, about 300 m E of the M31 and M57 junction, on the M31 next to the road (–CD), 15 Oct 2016, Le Roux 186 (PRE); near Premier Mine (−DA), 04 Oct 1963, Stauffer and Scheepers 5243 (PRE). 2627 (Potchefstroom): ± 4 km W of Carletonville on road to Potchefstroom (−AD), 26 Nov 2007, Burgoyne 10,951 (PRE); Rangeview, gedeelte van Witwatersrand Nasionale Botaniese Tuin, Krugersdorp bo-op rif agter Mev. Du Plessis se grond [part of Witwatersrand National Botanical Garden, Krugersdorp on top of ridge behind Mrs. Du Plessis' property] (–BB), 22 Oct 1987, Behr 951 (PRE); Robindale, park on corner of Bellairs Street and Gaiety Avenue (–BB), 14 Nov 1998, Reddy, Reddy and Reddy 1734 (J, PRE). 2628 (Johannesburg): Germiston (−AA), Sept 1913, Rogers 11,829 (PRE, BOL); near Rosebank (−AA), 24 Oct 1930, Fries 5356 (PRE); Benoni (–AB), 03 Nov 1934, Bradfield 268B (PRE); Oct 1929, Verdoorn 806 (PRE); at blockhouse near Engen 1-Stop Kliprivier (–AC), 23 Nov 2007, Burgoyne 10,914 (PRE); Wattles, Witwatersrand (–AC), 16 Oct 1924, Moss 10,507 (BM, PRE). MPUMALANGA: 2430 (Pilgrim's Rest): on road to Sekhukhune, NW of Maartenshoop (–CC), 12 Oct 2000, Meyer 3026 (PRE). 2529 (Witbank): Doornpoort 273 JS (–CB), 07 Jan 1969, Du Plessis 1270 (PRU), 08 Jan 1969, Du Plessis 1276 (PRU); farm Langkloof, ± 14 mi [22.4 km] NW of Middelburg (–CB), 08 Oct 1963, Codd 10,343 (PRE);

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Middelburg (–CD), Nov 1910, Jenkins 15,232 (PRE). 2530 (Lydenburg): Schoeman's Kloof, western end, upper slopes (–AD), 14 Nov 1933, Young A357 (PRE); 16 mi [25.7 km] SE of Lydenburg (–BA), 16 Aug 1966, Morris 47 (K, PRE); MacMac Pools (–BB), 23 Oct 1985, Hilliard and Burtt 18,453 (K, PRE); Kemp's Height, farm Lissbon (–BC), 27 Oct 2016, Visser and Le Roux 215/2 (PRE); 4.5 mi [7.2 km] N of Belfast (– CA), 10 Nov 1947, Codd and de Winter 3218 (PRE); Thorncroft Natuur Reservaat [Nature Reserve] (−DD), 06 Jan 1972, Muller 2308 (PRE). 2531 (Komatipoort): Saddleback Mountain, Barberton (–CC), Oct 1889, Galpin 581 (PRE). 2629 (Bethal): Bethal (−AD), Dec 1910, Leendertz 3623 (PRE); Standerton (–CC), 08 Nov 1915, Rogers 14,793 (BOL, J); Nooitgedacht 10 (–DB), 09 Dec 1926, Henrici 1248 (PRE); Uitspanning, Vermaakskraal farm (−DD), 30 Oct 1986, Turner 1149 (PRE). 2630 (Carolina): Carolina (−AA), 29 Oct 1932, Galpin 12,510 (PRE); Rooihoogte (Sappi), farm Victoriaspoort 18 IT, Kalkoenkrans Waterfall, ± 3.3 km NNW of trig beacon 56 (−AA), 07 Nov 2009, Makgakga, Masupa and Nonyane 522 (PRE). 2730 (Vryheid): Wakkerstroom (–AC), 20 Apr 1915, Beeton 43 (SAM); Wakkerstroom, Martin's Dam (–AC), 01 Nov 1985, Hilliard and Burtt 18,509 (K, PRE). FREE STATE: 2729 (Volksrust): 1 mi [1.6 km] W of top of Normandien Pass (–DC), 13 Feb 1966, Acocks 23,812 (PRE). 2828 (Bethlehem): Bethlehem (–AB), 1964, Smit 57 (PRE); Golden Gate National Park, Generaalskop (−DA), Jan 1963, Liebenberg 6928 (PRE). 2829 (Harrismith): Drakensberg Botaniese Tuin [Botanical Garden] (–AC), 20 Nov 1974, Jacobsz 2077 (NBG, PRE); farm Rensburgskop (–AC), 31 Oct 1979, Jacobsz 676 (PRE). KWAZULU-NATAL: 2729 (Volksrust): Groenvlei, ± 4 km to Utrecht/Vryheid T-junction from Newcastle (–DB), 20 Nov 1997, Ngwenya 1671 (NH); Ncandu Reserve, ± 1.5 km to Hiker's Cottage (–DC), 19 Nov 1997, Ngwenya 1650 (NH). 2730 (Vryheid): Retirement, Utrecht (−AD), 17 Oct 1962, Devenish 908 (PRE). 2829 (Harrismith): Van Reenen Pass, farm Nolans Volens (−AD), 09 Dec 1976, Hilliard and Burtt 9430 (K, PRE); Bergville: Tugela valley, Drakensberg National Park (–CD), 29 Oct 1938, Hafström and Acocks 468 (PRE). 2929 (Underberg): Cleft path, Cathedral area, Drakensberg (−AA), Oct 1944, Schelpe 845 (NH); Tabamhlope Research Station (– BA), 26 Nov 1937, West 472 (PRE); Giant's Castle (–BC), 06 Nov 1897, Bolus 4954 (BOL), Oct 1914, Symons 74 (PRE); Giant's Castle Game Reserve (en route to the Giant) (–BC), 14 Nov 1966, Trauseld 690 (PRE); Highmoor Forest Reserve, ridge SE of Giant's Castle headwaters of Elandshoek River (–BC), 05 Jan 1983, Hilliard and Burtt 16,206 (PRE); Chameleon Cave area, 5 mi [8 km] N of Castle View farm (–CB), 01 Dec 1984, Hilliard and Burtt 17,758 (PRE); Cobham Forest Station, Ndlovini, Troutbeck (–CB), 08 Nov 1980, Hilliard and Burtt 13,360 (PRE, NBG); Cobham, road to Drakensberg Garden (–CB), 28 Nov 1976, Hilliard and Burtt 9411 (K, PRE); Cobham State Forest Reserve, “Lakes” cave area (–CB), 11 Dec 1982, Manning, Hilliard and Burtt 15,902 (PRE); Gxalingenwa valley, between Sani Pass and Polela valley (–CB), 11 Dec 1983, Hilliard and Burtt 17,190 (PRE); upper tributaries, S of Mkomazi River (feeders of Ka-Ntubu) (–CB), 02 Dec 1982, Hilliard and Burtt 15,778 (K, PRE); Drakensberg Garden, grassland behind Hotel, hill to W side of tributary (–CC), 31 Jan 2017, Visser, Le Roux and Nickrent 247 (PRE); vicinity of Tarn Cave, above Bushman's Nek (–CC), 20 Nov 1983, Hilliard and Burtt 16,807 (K, NBG, PRE); Bamboo Mountain, S side above Restmount (–CD), 20 Nov 1982, Hilliard and Burtt 15,580, 15,581 (K, PRE); Drakensberg Garden area, next to road 17.8 km from R617 to Drakensberg Garden (–CD), 31 Jan 2017, Visser, Le Roux and Nickrent 251 (PRE); Hlogoma Mountain, plot 20 mi [32.2 km] W facing slope below second ridge (–DC), 04 Oct 2014, Berruti 395 (NH). 2930 (Pietermaritzburg): Mt. Gilboa, near summit (−AD), 29 Dec 1978, Hilliard and Burtt 11,850 (NBG); Noodsberg, Laager farm (–BD), 14 Oct 1989, Williams 559 (PRE, NH); past Polly Shorts, Ashburton (–CB), 25 Sep 1974, Stirton 1138 (PRE). 3029 (Kokstad): Nsikeni, edge of vlei (–AB), 28 Oct 1993, Abbott 6061 (PCE); Ngele Mountain, Bulldozer draai (−DA), 12 Oct 1991, Abbott 5555 (NH, PCE).

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Lesotho. 2828 (Bethlehem): Leribe (–CC), Dec 1910, Dieterlen 462A (PRE, SAM). 2929 (Underberg): Sehlabathebe National Park, S side of crater, above road (–CC), 28 Oct 1976, Hoener 1583 (PRE). 2. T. gracilarioides A.W.Hill in Bull. Misc. Inform. Kew 1: 29 (1915); A.W.Hill in Dyer, Fl. Cap. 5(2): 183 (1925); N.E.Br. in Burtt Davy, Man. Pl. Transvaal 2: 461 (1932); Retief and P.P.J.Herman in Plants of the northern provinces of South Africa: 597 (1997). Type: South Africa, Mpumalanga, Komatipoort (2531): on stony mountain sides, Saddleback, Barberton (–CC), 09 Oct 1889, Galpin 543 (K, lecto.!, designated here; PRE [2 sheets]!, isolecto.). Other original material: Swaziland, Komatipoort (2531): Havelock Concession (–CC), 15 Sep 1890, Saltmarshe 1048 (K, syn.!, PRE, syn.!). [Note: Galpin 543 (K) was chosen as the lectotype of T. gracilarioides as the specimen is named and annotated by A.W.Hill, a duplicate is housed in PRE and it represents the characteristic form of T. gracilarioides]. Robust rhizomatous suffrutex, up to 1 m tall, vegetative scales present on rhizome and lower parts of aerial stems, stems 2 to 16, arising from rhizome at intervals, erect at lower elevations, spreading and decumbent at higher elevations, branched, changing from green to yellow-orange as stems age, very prominently sulcate distally through decurrent leaves, becoming slightly sulcate to terete below, densely leafy (14–40 leaves per 50 mm at middle of stem). Leaves spreading, linear or linear-lanceolate, 3.0–14.5 × 0.3–1.0 mm, apex acuminate and usually cartilaginous, midrib raised on upper leaf surface but less so on lower leaf surface, margins entire. Flowers solitary in bract axils, arranged in 4 to 10-flowered monotelic racemose inflorescences, occasionally terminating in simple dichasial or monochasial cymes; pedicels 0.0–1.5 mm long. Bracts linear-lanceolate, 3.7–7.0 × 0.4–0.7 mm, acuminate, margins entire, fused to 2/3 of pedicel or entire pedicel; bracteoles 2.3–3.2 × 0.2–0.6 mm. Perianth 2.3–3.1 mm long, elongate receptacle absent, “glands” often visible on outside; lobes narrowly triangular, 0.8–1.0 × 0.3–0.7 mm, apex slightly hooded, with more or less dense apical beard. Stamens inserted in perianth tube; filaments 0.1– 0.5 mm long; anthers 0.2–0.7 mm long. Style 0.0–0.4(0.7) mm long, stigma ± opposite anthers, occasionally below anthers. Placental column straight. Fruit sessile, 3.0–5.0 mm long including persistent perianth (2.5–4.0 mm long excluding perianth), 1.6–2.4 mm wide, with prominent reticulate venation. Distribution and ecology Thesium gracilarioides occurs in Swaziland and South Africa, where it has been collected in the mountains around Barberton and from other mountain ranges in the north-eastern part of South Africa, namely the Waterberg and Soutpansberg in Limpopo, and the Magaliesberg in North West (Fig. 7B). It occurs in mountainous areas at elevations between 1640 and 1890 m a.s.l., typically in rocky areas in open grasslands and on steep slopes. Flowering time is between August and April. Diagnostic characters Thesium gracilarioides is commonly confused with T. gypsophiloides, the only other species in the complex with similarly short styles (Fig. 6A1) and stamens inserted in the perianth tube (Fig. 6A2). Thesium gracilarioides was previously thought to occur sympatrically with T. gypsophiloides but T. gracilarioides occurs mainly in Mpumalanga and Limpopo between 1640 and 1890 m a.s.l., thus at higher altitudes and north of T. gypsophiloides, which is restricted to between 152 and 610 m a.s.l. in KwaZulu-Natal. In addition to the geographical separation, T. gracilarioides has a very leafy habit (14–40 leaves per 50 mm at the middle of the stem) (Fig. 5B), grows to a maximum height of 1 m, has small leaves 3.0–14.5 × 0.3–1.0 mm, and has short racemose inflorescences occasionally terminating in simple-dichasial or monochasial cymes, with bracts fused to 2/3 of the pedicel or to the entire pedicel. In contrast, T. gypsophiloides is moderately leafy (4–12 leaves per 50 mm at

the middle of the stem), grows up to 2 m tall, has larger leaves (7.0) 9.0–19.5(25.5) × 0.6–2.0 mm (Fig. 6C), and has compound monochasial cymose inflorescences with very long peduncles (2.7)5.7–17.5 mm long (Fig. 2E), with bracts fused to only 1/2 of the peduncle (Fig. 2E). Conservation status Thesium gracilarioides is abundant and widespread and is therefore appropriately classified as Least Concern (IUCN Standards and Petitions Subcommittee, 2017). Additional specimens examined South Africa. LIMPOPO: 2229 (Waterpoort): Zoutpansberg [Soutpansberg] (–DC), Rogers 21,549 (K). 2329 (Pietersburg): Vivo, farm Llewellyn 35 (–AB), 04 Jul 1985, Venter 10,720 (PRE). 2428 (Nylstroom): Mosdene, Naboomspruit (–DB), 19 Jan 1919, Galpin M315 (PRE). NORTH WEST: 2527 (Rustenburg): Jacksonstuin, noord liggende kloof Magaliesberg [N facing valley Magaliesberg] (−DA), 01 Aug 1957, Van Vuuren 263 (PRE). MPUMALANGA: 2530 (Lydenburg): Starvation Creek Nature Reserve (−DA), 27 Oct 1977, Kluge 1102 (PRE); Castle Kop, 10 mi [16.1 km] NW Barberton (–DB), 11 Oct 1963, Stauffer and Weder 5278 (K, PRE); Kaapschehoop (–DB), 24 Oct 1985, Hilliard and Burtt 18,466 (PRE); 11 Oct 1963, Stauffer and Weder 5282 (K, PRE). 2531 (Komatipoort): 14 km from Barberton, on Havelock Road, Saddleback Ridge (–CC), 04 Mar 1987, Retief 2130 (PRE); about 15 km SE of Barberton on Barberton Havelock road (–CC), 19 Mar 1992, Balkwill and Robinson 6845 (J); Barberton (–CC), Nov 1915, Rogers 18,269 (K); 26 Oct 1938, Hafström and Acocks 466 (PRE); Barberton, above Lone Tree Hill (–CC), 29 Oct 1985, Hilliard and Burtt 18,497 (PRE); Barberton, Duiwels Kantoor [Devil's Office] (–CC), Oct 1928, Thode A1638 (K, PRE); hilltop E of Dycedale admin centre, farm Dycedale 368 JU (–CC), 29 Oct 2016, Visser and Le Roux 223, 224 (PRE); Kangwane, Songimvelo Game Reserve, Mendon boundary with Schultzenhorst (–CC), 09 Dec 1992, Germishuizen 5806 (PRE); steep road verge between the Mountainlands entrance gate and admin building, farm Dycedale 368 JU, Mountainlands Nature Reserve (–CC), 29 Oct 2016, Visser and Le Roux 222 (PRE). 2630 (Carolina): Castle peak, Ngwenya hills, 13 mi [20.9 km] NW of Mbabane (–BB), 06 Apr 1966, Maguire 7511, 7601 (J). Swaziland. 2631 (Mbabane): Bomvu Ridge (−AA), 18 Nov 1958, Compton 28,367 (PRE); Ngwenya mountains (hills) (−AA), 30 Jan 1957, Compton 26,525 (PRE). 3. T. gracile A.W.Hill in Bull. Misc. Inform. Kew 6: 185 (1910); Baker and A.W.Hill in Dyer, Fl. Trop. Afr. 6(1): 419 (1911); N.E.Br in Burtt Davy, Man. Pl. Transvaal 2: 462 (1932); Retief and P.P.J.Herman in Plants of the northern provinces of South Africa: 597 (1997); Hilliard in Fl. Zambes. 9(3): 232 (2006). Type: Zimbabwe, Sebakwe (1930AA), Dec 1904, Eyles 85 (BM, lecto.!, designated by Hilliard: 232 (2006); K!, SRGH, isolecto.). T. palliolatum A.W.Hill in Bull. Misc. Inform. Kew 6: 187 (1910); Baker and A.W.Hill in Dyer, Fl. Trop. Afr. 6 (1): 417 (1911); A.W.Hill in Dyer, Fl. Cap. 5(2): 184 (1925). Type: Mozambique, lower Zambezi (1735): Sena [Villa de Senna] (–AC), Jan 1859, Kirk s.n. (K, holo.!). Rhizomatous suffrutex, up to 0.3 m tall, vegetative scales present on rhizome and lower parts of aerial stems, stems 4 to 16, arising from rhizome at intervals, suberect or occasionally spreading, slender, branched, green, sulcate distally through decurrent leaves, often terete below, moderately leafy (5–10 leaves per 50 mm at middle of stem). Leaves more or less spreading, young leaves can be adpressed, linear, 4.0– 17.0 × 0.3–1.0 mm, apex acute-acuminate and usually cartilaginous, midrib raised on both surfaces, margins entire. Flowers in simple or compound 3-flowered dichasial cymes, or occasionally monochasial cymes; cyme peduncles 2.0–8.0(18.0) mm long. Bracts linear-

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Fig. 6. Diagnostic characters of some of the species in the Thesium goetzeanum complex. A. T. gracilarioides: (1) style short or occasionally sessile and (2) stamens inserted in the perianth tube. B. T. gracile: cymose inflorescences with (1) long peduncles and (2) bracts fused to 1/4 or less of the peduncle. C. T. gypsophiloides: leaves large, linear-lanceolate to lanceolate-ovate. D. T. infundibulare: flower with elongate receptacle. E. T. infundibulare: (1) stipitate fruit and (2) reticulation faint or absent. F. T. lobelioides: large flowers with prominently long lobes. G. T. vahrmeijeri: stipitate fruit. The scale bars represent 1 mm.

lanceolate, 2.5–7.5 × 0.2–0.6 mm, acute, margins entire, fused to 1/8–1/ 4 of peduncle; bracteoles 1.4–3.0 × 0.2–0.4 mm. Perianth 1.8–3.0 mm long, receptacle occasionally slightly elongate, “glands” often visible on outside; lobes narrowly triangular, 0.8–0.9 × 0.7–0.4 mm, apex very slightly hooded, with sparse apical beard. Stamens inserted at base of tepals; filaments 0.2–0.4 mm long; anthers 0.2–0.5 mm long. Style 0.2–0.6 mm long, stigma ± opposite anthers. Placental column straight. Fruit sessile, 3.0–4.0 mm long including persistent perianth (2.5–3.6 mm long excluding perianth), 2.2–2.5 mm wide, with prominent reticulate venation.

Distribution and ecology Thesium gracile is found in Mozambique, South Africa and Zimbabwe. In South Africa, its distribution overlaps with both T. resedoides and T. gracilarioides, encompassing the eastern parts of Limpopo and Mpumalanga, with an outlier at Brits in North West (Fig. 7C). Thesium gracile is usually found in open, rocky patches of grassland in wooded

areas, at elevations between 457 and 1676 m a.s.l. Flowering time is between November and April. Diagnostic characters Thesium gracile is most likely to be confused with the superficially similar T. resedoides as their distributions overlap and they have similar growth forms. Thesium gracile is distinguished from T. resedoides by its cymose inflorescences (Fig. 2D; usually compound dichasia or occasionally compound monochasia) accompanied by longer peduncles 2–8 mm long (Fig. 6B1), and bracts fused to about 1/4 of the peduncle (Fig. 6B2), while T. resedoides has predominantly racemose inflorescences borne on shorter peduncles up to 3 mm long with fully fused bracts. Conservation status Thesium gracile is abundant and widespread and is therefore appropriately classified as Least Concern (IUCN Standards and Petitions Subcommittee, 2017).

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Fig. 7. Known geographic distributions of the 10 species in the Thesium goetzeanum complex. A. T. goetzeanum. B. T. gracilarioides. C. T. gracile. D. T. gypsophiloides. E. T. infundibulare. F. T. lobelioides. G. T. procerum. H. T. resedoides and I. T. vahrmeijeri.

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Fig. 7 (continued).

Additional specimens examined South Africa. LIMPOPO: 2328 (Baltimore): Lebowa, Blouberg Mountain, Buffelshoek farm 261 LR on SW side of massif on Blouberg geological series (–BB), 07 Dec 1990, Smook 7373 (PRE). 2329 (Pietersburg): Soekmekaar-Bandelierskop (–BD), 06 Feb 1976, Brenan 14,129 (K, PRE); Mooketsi, farm Vreedsaam (–DB), 06 Feb 1976, Brenan 14,135 (K, PRE). 2330 (Tzaneen): Mooketsi (–CA), 06 Feb 1976, Brenan 14,134 (PRE); Letsitele, Letaba River bank (–CD), 01 Oct 1975, Balsinhas 2785 (K). 2331 (Phalaborwa): Kruger National Park, Nahpe (–DC), 22 Jan 1935, Van der Schijff 1551 (PRE). 2429 (Zebediela): Potgietersrus [Mokopane] (−AA), Feb 1904, Bolus 11,008 (K); 11–13 km SE of Potgietersrus, farm Nederland 51 KS, near boundary with Vierentwintig Rivier (–AC), 21 Dec 1974, Maguire 8621 (J). 2430 (Pilgrim's Rest): Thubatse, exit gate at back of town, follow gravel road on right next to fence (–CB), 13 Feb 1998, Siebert 308 (PRU); area to E of hill opposite Richmond turn-off (–CC), 10 Dec 1998 Siebert 647 (J, PRU). 2431 (Acornhoek): Hermitage, Manyeleti Game Reserve (−DA), 17 Mar 1977, Bredenkamp 1775 (PRE). NORTH WEST: 2527 (Rustenburg): Beestekraal Game Reserve near Atlanta Station (–DB), 13 Oct 1990, Barker 912 (PRE). MPUMALANGA: 2430 (Pilgrim's Rest): Blyderivierpoort Natuur Reservaat, Rietvlei plaas [Blydepoort Nature Reserve, Rietvlei farm] (−DA), 09 Nov 1998, Zietsman 3695 (PRE, PRU); Krugerspost (–DC), 20 Nov 1933, Young A495 (PRE). 2529 (Witbank): ± 10 km WSW from Belfast, Langkloof farm (−DD), 30 Jan 1996, Burgoyne 3970 (PRE). 2530 (Lydenburg): Lowveld Botanic Garden (–BD), 24 Nov 1969, Buitendag 346 (PRE); Kaapschehoop (–DB), Mar 1918, Rogers 20,952 (PRE). 2531 (Komatipoort): Kruger National Park, 11 mi [17.7 km] ENE of Pretorius Kop (–AB), 13 Jan 1953, Acocks 16,653 (K, PRE); Kruger National Park, near Pretorius Kop (–AB), 04 Feb 1949, Codd and de Winter 4932 (K, PRE); ± 3 mi [4.8 km] E Nelspruit (–AC), 11 Oct 1963, Stauffer and Weder 5267 (K, PRE); ±6 mi [9.7 km] E Nelspruit, N der Strasse [N of road] (–AC), 12 Oct 1963, Stauffer and Weder 5268 (K, PRE); by Komati River (–BD), Aug 1886, Bolus 9765 (K); Barberton phase 2, Mundt's Concession (–CA), 22 Jan 1998, Williamson 619 (J), 28 Nov 1998; Williamson 796 (J), 28 Nov 1998; Williamson 812 (J); Old Coach Road House, Barberton, behind rooms 6 and 7 under large powerlines (–CA), 28 Oct 2016, Visser and Le Roux 221 (PRE); Bon Venue 255JU farm, neck and E facing hill slope of highest of Three Sisters mountains (–CB), Oosthuizen H2264(A) (PRE); Kaapmuiden (–CB), Dec 1921, Rogers 25,046 (PRU); Barberton (–CC), Nov 1909, Williams 7624 (K, PRE). 4. T. gypsophiloides A.W.Hill in Bull. Misc. Inform. Kew 1: 30 (1915); A.W.Hill in Dyer, Fl. Cap. 5(2): 185 (1925); N.E.Br. in Burtt Davy, Man. Pl.

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Transvaal 2: 462 (1932); Retief and P.P.J.Herman in Plants of the northern provinces of South Africa: 598 (1997). Type: South Africa, KwaZuluNatal, Port Shepstone (3030): Umtwalumi [Mtwalume] (–BC), 22 Apr 1884, Medley-Wood 3105 (K, lecto.!, designated here; BOL – image!, NH – image!, iso-lecto.). Other original material: South Africa, KwaZuluNatal, Pietermaritzburg (2930): Natal, precise locality unknown, likely in the area of Verulam and Inanda (–DB), Medley-Wood 576 (NH, syn. – image!). Port Shepstone (3030): Umtwalumi [Mtwalume] (–BC), 22 Apr 1884, Medley-Wood 573 (BM, syn.!; BOL, syn.!; NH, syn. – image!). Precise locality unknown, likely near Durban, Gerrard 407 (BM, syn.!, K, syn.!). [Note: Hill (1915) provided a collection of mixed syntypes in the protologue of T. gypsophiloides. This has resulted in considerable confusion concerning the circumscription of this species (Brown, 1932). In concurrence with the suggestion by Brown (1932), the true T. gypsophiloides noted here corresponds with the following syntypes from the protologue: Medley-Wood 576, 3105 and Gerrard 407. Medley-Wood 3105 (K) is designated as the lectotype here (duplicates are housed in BOL and NH). Galpin 758 is likely an extreme form of T. resedoides. This conclusion is supported by its locality in Barberton, which is within the known distribution range of T. resedoides and relatively far removed from the distribution of T. gypsophiloides in KwaZulu-Natal]. Shrub, up to 2 m tall, with a woody rootstock but lacking a rhizome, vegetative scales absent from rootstock and lower parts of the stems, stems 1 to 13, erect or suberect, abundantly branched, sulcate to angular distally through decurrent leaves, becoming terete below, brown in lower parts and green in upper parts, moderately leafy (4–12 leaves per 50 mm at middle of stem). Leaves usually spreading, linear-lanceolate or larger leaves occasionally lanceolate to ovate-lanceolate, (7.0) 9.0–19.5(25.5) × 0.6–2.0 mm, apex acute to acuminate and usually not cartilaginous, midrib raised on both surfaces, margins often scabrous. Flowers in compound monochasial and occasionally dichasial cymes resembling scorpioid cymes, cyme peduncles (2.7)5.7–17.5 mm long. Bracts linear-lanceolate or lanceolate-ovate, 2.4–7.5(9.8) × 0.3–1.0 mm, acute-acuminate, margins often scabrous, usually fused to about 1/2 of peduncle; bracteoles 0.9–4.6 × 0.2–0.5 mm. Perianth 1.7–2.3 mm long, receptacle occasionally slightly elongate, “glands” often visible on outside; lobes lanceolate to narrowly triangular, 0.6–1.1 × 0.2– 0.4 mm, apex hooded, with apical beard. Stamens inserted in perianth tube; filaments 0.1–0.2 mm long; anthers 0.2–0.3 mm long. Style 0.1– 0.3 mm long, stigma ± opposite anthers. Placental column straight. Fruit sessile or occasionally stipitate, 4.3–5.3 mm long including persistent perianth (3.5–4.5 mm long excluding perianth), 2.0–3.0 mm wide, with prominent reticulate venation. Distribution and ecology Thesium gypsophiloides is endemic to KwaZulu-Natal in South Africa, where it occurs between the Hlatikulu Forest Reserve in the north and Mtwalume in the south (Fig. 7D). It occurs in grassland patches close to woodland areas, at elevations between 152 and 610 m a.s.l. Flowering time is between October and April. Diagnostic characters Thesium gypsophiloides is often confused with T. gracilarioides and T. resedoides where their distribution ranges overlap in northern KwaZulu-Natal but is easily distinguished by its thick (up to 10 mm diam.) woody stems that grow up to 2 m tall (Fig. 5I), the absence of vegetative scales (Fig. 1H), large linear-lanceolate leaves (7)9–19.5(25.5) × 0.6–2 mm (Fig. 6C), and compound monochasial cymose inflorescences with long peduncles (2.7)5.7–17.5 mm long tending towards the arrangement of scorpioid cymes (Fig. 2E). Thesium gracilarioides has slender stems up to 5 mm diam. growing to a maximum height of 1 m (Fig. 5B), with vegetative scales on the root and lower parts of the stems, smaller linear or linear-lanceolate leaves 3.0–14.5 × 0.3–1.0 mm, and short racemose inflorescences. Thesium resedoides has similar slender

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stems up to 3 mm diam. growing to a maximum height of 0.4 m (Fig. 5D), vegetative scales on the root and lower parts of the stems, smaller, linear leaves 4.5–22.5(26.0) × 0.3–2.3 mm, and racemose inflorescences with short pedicels (0.0)0.5–3.0 mm long. Thesium gypsophiloides and T. gracilarioides are also altitudinally separated as they occur between 152 and 610 m a.s.l. and 1640–1890 m a.s.l., respectively. Conservation status Thesium gypsophiloides is known from only five locations, but its extent of occurrence exceeds 20,000 km2. The populations are fragmented and continue to decline due to ongoing habitat loss at Umtwalumi, Wilson Channel, and the two localities in the vicinity of Verulam and Durban. Data on subpopulations are lacking and more field surveys may reveal that it qualifies for a higher category of threat under Criterion C. Insufficient data is available to assess T. gypsophiloides against Criteria A, C, D and E. Therefore, based on currently available data, we suggest a classification of Near Threatened as it nearly meets the thresholds for Vulnerable under Criterion B (IUCN Standards and Petitions Subcommittee, 2017). Thesium gypsophiloides was previously listed as Least Concern (Raimondo et al., 2009). Additional specimens examined South Africa. KWAZULU-NATAL: 2731 (Louwsburg): Itala Nature Reserve, ± 2 mi [3.2 km] from Bivane-Pongola Junction on track to warden's house (–CB), 09 Jan 1976, Brown and Shapiro 379 (PRE, K). 2732 (Ubombo): Lebombo Mountains, Gwalaweni forest [Hlatikulu Forest Reserve, Gwaliweni] (–AC), 15 Feb 1976, Brenan 14,274 (K). 2831 (Nkandla): Station Dumisa, Umgoye [Ngoye Forest] (–DC), 24 Oct 1909, Rudatis 768 (BM, K). 2832 (Mtubatuba): Lower Umfolozi, near Wilson Channel, Monzi sandy hills (−AD), 20 Jan 1965, Strey 5678 (PRE). 3030 (Port Shepstone): Vernon Crookes Nature Reserve, E of picnic site, about 30 m from edge of forest patch (–BC), 03 Feb 2017, Visser and Le Roux 269 (PRE). 5. T. infundibulare N.Visser and M.M.le Roux sp. nov. Type: Swaziland, Komatipoort (2531): Malolotja Nature Reserve, ridge W of Mgwayiza road, N of road before stream crossing, rock outcrop area next to old track (–CC), 16 Nov 1993, Braun 1636 (PRE, holo.). Suffrutex, ±0.3 m tall, rootstock not seen, vegetative scales present on lower parts of stems, stems erect, with vegetative shoots overtopping inflorescences, branched in upper 2/3, sulcate, greyishgreen, sparingly leafy to moderately leafy (5–16 leaves per 50 mm at middle of stem). Leaves spreading, dimorphic, those in lower 2/3 of stems, lanceolate, 12.5–27.0 × 1.1–2.8 mm, those in upper 1/3 of stems, linear, 5.0–14.0 × 0.5–1.0 mm, all leaves with midrib raised on both surfaces, apex acute-acuminate and usually cartilaginous, margins entire. Flowers usually solitary in bract axils, arranged in 4 to 9-flowered monotelic, racemose inflorescences, occasionally terminating in simple 3-flowered dichasial cymes; pedicels 0.5–3.0 mm long. Bracts linearlanceolate, 5.3–10.0 × 0.4–1.4 mm, acute, margins entire, fused to entire pedicel; bracteoles 2.7–6.8 × 0.3–1.0 mm. Perianth 3.6–5.2 mm long, receptacle elongate, “glands” often visible on outside; lobes narrowly triangular to triangular, 1.2(1.8) × 0.4–0.7 mm, apex hooded, with dense apical beard. Stamens inserted at base of tepals; filaments 0.3–0.5 mm long; anthers 0.5–0.9 mm long. Style 1.0–1.5 mm long, stigma ± opposite anthers. Placental column straight. Fruit stipitate, 6.2–7.0 mm long including persistent perianth (3.9–4.5 mm long excluding perianth), 2.8–3.0 mm wide, smooth or with faint reticulate venation. Distribution and ecology Thesium infundibulare is known from five collections, with its distribution limited to the western part of Swaziland and the northern inland

side of KwaZulu-Natal, South Africa (Fig. 7E). It has been found on rocky outcrops at elevations between 600 and 1000 m a.s.l. Flowering time is in October and November. Diagnostic characters Thesium infundibulare is most likely to be confused with T. resedoides, from which it is distinguished by stems branching only in the upper 2/3 (Fig. 5H1), dimorphic foliage with large leaves on the lower 2/3 of the stems (Fig. 5H2), leafy vegetative shoots overtopping the inflorescences (Fig. 5H3), flowers with an elongate receptacle (Fig. 6D), and stipitate fruits (Fig. 6E1) with little or faint reticulation (Fig. 6E2). Thesium resedoides shows no specific branching pattern, lacks larger leaves on the lower part of the stems, has no vegetative shoots overtopping the inflorescences, has no elongated receptacle, and has sessile, usually reticulately veined fruit. Thesium infundibulare is named for the habit of the plant, with stems branching only in the upper two thirds of the plant, giving it the shape of a funnel. Specimens tend to dry blackish. Conservation status The extent of occurrence of Thesium infundibulare is 3860 km2, although the species is still poorly sampled and more field surveys are required. It is known from only five locations, two of which (Vryheid in South Africa and Dalriach in Swaziland) are experiencing ongoing habitat loss and degradation. Based on available data, we suggest a conservation status of Near Threatened under Criterion B (IUCN Standards and Petitions Subcommittee, 2017). Additional specimens examined South Africa. KWAZULU-NATAL: 2730 (Vryheid): top of Hlobane Mountain, 25 km E of Vryheid, N of Hlobane mine (–DB), 09 Dec 1996, Robbeson 292 (PRU). Swaziland. 2631 (Mbabane): Dalriach (–AC), 18 Nov 1957, Compton 27,224 (PRE, SAM); Hlatikulu, (–CD), Oct 1910, Stewart 10,082 (PRE); Kubuta (–CD), 15 Oct 1959, Compton 29,227 (NBG). 6. T. lobelioides A.DC. in Esp. Nouv. Thesium: 8 (1857); A.DC. in Prodr. 14: 666 (1857); A.W.Hill in Dyer, Fl. Cap. 5(2): 181 (1925); Retief and N.L.Mey. in Plants of the Free State: 751 (2017). T. recurvifolium Sond. in Flora 40: 356 (1857). Type: South Africa, Eastern Cape, Fort Beaufort (3226): Ceded Territory, bei Philipstown am Katrivier [at Philipstown next to Kat River] (–DC), Oct 1933, Ecklon and Zeyher 25 (S, holo. – image!; K!, MO – image!, W – image!, iso.). Robust suffrutex, up to 0.3 m tall, rootstock and lower parts of stems not seen, stems 1 to 2 (11), erect or suberect, branched, sulcate, light mauve or greyish in colour, moderately leafy (6–11 leaves per 50 mm at middle of stem). Leaves slightly spreading, linear, or occasionally linear-lanceolate, 5.0–20.0 × 0.5–1.2 mm, apex acute, often recurved and usually not cartilaginous, midrib often raised on both surfaces, margins entire. Flowers solitary in bract axils, arranged in 6 to 14-flowered monotelic racemose inflorescences, often terminating in 2(3)-flowered monochasial cymes; pedicels (0.0)0.5–2.0 mm long. Bracts linear-lanceolate, 7.0–13.0 × 1.2–1.8 mm, apex acute-acuminate, margins often scabrous, fused to entire pedicel; bracteoles 4.5–7.0 × 0.2–0.9 mm. Perianth 4.0–5.5 mm long, elongate receptacle absent, “glands” often visible on outside; lobes linear to narrowly triangular, occasionally with a prominent midrib, 1.3–2.2 × 0.3–1.2 mm, apex slightly hooded, with dense apical beard. Stamens inserted at base of tepals; filaments 0.4–0.5 mm long; anthers 0.5–0.6 mm long. Style 1.3–1.6 mm long, stigma ± opposite anthers. Placental column straight. Fruit sessile, ± 7.0 mm long including persistent perianth (± 4.5 mm long excluding perianth), ± 3.0 mm wide, with prominent reticulate venation.

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Distribution and ecology

Distribution and ecology

Thesium lobelioides is endemic to South Africa, where it is poorly collected and known only from Thaba Nchu in the Free State and near the Kat River in the Eastern Cape (Fig. 7F), in grasslands at elevations between 610 and 1980 m a.s.l. Flowering time is between October and January.

Thesium procerum has only been recorded in South Africa, between Heidelberg in Gauteng, Mokopane in Limpopo, Zeerust in North West and Nelspruit in Mpumalanga (Fig. 7G). This species is found primarily on steep hillsides and rocky ridges in bushveld and shrubland areas, between elevations of 1450 and 1768 m a.s.l. Flowering time is between September and February (June).

Diagnostic characters Diagnostic characters Thesium lobelioides has the largest flowers in the complex, 4.0–5.5 mm long, with very long, linear tepals, 1.3–2.2 mm long (Fig. 6F). It superficially resembles T. resedoides but that species has smaller flowers, 2.5–3.3(5.0) mm long, with shorter narrowly triangular lobes, 1.1–1.5 mm long. Hill (1925) noted that T. lobelioides is “purplish or grey” in colour and the specimen from Thaba Nchu is indeed mauve. This colour is unique within the T. goetzeanum complex (glaucous or green in other species) and is therefore evidently diagnostic. The distributions of T. lobelioides and T. resedoides are allopatric as they occur in grassland in the Eastern Cape and Free State, and in savanna in the northern provinces of the country, respectively. Conservation status Thesium lobelioides is severely under-sampled and is known from only two widely separated localities. These two collections date from 1933 and 1964, respectively, and no recent collections are available. Data on the abundance and habitat of T. lobelioides are also lacking. We suggest that this species be listed as Data Deficient because its risk of extinction cannot be determined based on the current available data (IUCN Standards and Petitions Subcommittee, 2017). Thesium lobelioides was previously listed as Least Concern (Raimondo et al., 2009) because it was routinely misidentified as T. resedoides which is abundant and widespread.

Thesium procerum is a large, much-branched, spreading shrub up to 1.5 m tall (Fig. 5G), which is characterised by its sparsely leafy (5–10 (16) leaves per 50 mm at middle of stem) and terete stems, racemose inflorescences with abundant 2- or 3-flowered monochasia and occasional 3-flowered dichasia (Fig. 2B, C), flowers with stamens inserted at the base of the tepals, twisted placental columns (Fig. 3B) and stipitate fruits (Fig. 1J). Thesium gracilarioides and T. gypsophiloides are the only other species in the complex that grow taller than about 0.3 m. Thesium procerum is geographically separated from T. gypsophiloides which is restricted to KwaZulu-Natal and differs in its moderately leafy (4 to 12 leaves per 50 mm at middle of stem) and sulcate stems, compound monochasial and dichasial cymes which resemble scorpioid cymes (Fig. 2E), flowers with stamens inserted in the perianth tube, straight placental columns and sessile, or occasionally shortly stipitate fruits. Thesium gracilarioides occurs sympatrically with T. procerum and has a similar inflorescence structure but its leafy (14 to 40 leaves per 50 mm at middle of stem) and sulcate stems, flowers with stamens inserted in the perianth tube (Fig. 6A2), straight placental columns and sessile fruits separates it from T. procerum. Older plants of T. procerum have thick woody stems and are densely branched (Fig. 5G), whereas young plants are recognised by their terete, glaucous stems spreading from a woody base. A brown discolouring is very often present on older herbarium specimens where the branches are in contact with the paper.

Additional specimens examined Conservation status South Africa. FREE STATE: 2926 (Bloemfontein): Thaba Nchu mountain, Groothoek (–BD), 09 Jan 1964, Roberts 2987 (PRE). 7. T. procerum N.E.Br. in Burtt Davy, Man. Pl. Transvaal 2: 462 (1932); Retief and P.P.J.Herman in Plants of the northern provinces of South Africa: 598 (1997). Type: South Africa, Gauteng, Pretoria (2528): Premier Mine (−DA), 13 Oct 1917, Rogers 30,021 (PRE, holo.!). Robust rhizomatous shrub, up to 1.5 m tall, vegetative scales present on rhizome and lower parts of stems, stems 1 to 13, arising from rhizome at intervals, spreading or rarely suberect, abundantly branched, terete or faintly sulcate, brown below and glaucous-green above, usually sparsely leafy (5–10(16) leaves per 50 mm at middle of stem). Leaves slightly spreading, linear to linear-lanceolate, 3.0–11.0 × 0.2– 0.9 mm, apex acute-acuminate and usually not cartilaginous, midrib raised on lower surface, less pronounced on upper surface, margins entire. Flowers in 4 to 16-flowered monotelic racemose inflorescences, with abundant 2 to 3-flowered monochasia and occasional 3-flowered dichasia, inflorescences often compressed; pedicels 0.0–1.5 mm long; cyme peduncles 1.0–4.5(6.0) mm long. Bracts linear-lanceolate, 4.3– 5.5 × 0.4–0.8 mm, apex acute-acuminate, margins entire, fused to 2/3 or entire pedicel/peduncle, occasionally fused to ±1/2 of cyme peduncles; bracteoles 2.5–3.5 × 0.3–0.5 mm. Perianth 2.5–4.0 mm long, receptacle elongate, “glands” occasionally visible on outside; lobes lanceolate to narrowly triangular, 0.9–1.3 × 0.3–0.7 mm, apex hooded, with sparse apical beard. Stamens inserted at base of tepals; filaments 0.2–0.4 mm long; anthers 0.4–0.6 mm long. Style 0.6–0.8 mm long, stigma ± opposite anthers. Placental column twisted. Fruit stipitate, 5.0–7.0 mm long including persistent perianth (3.5–5.5 mm long excluding perianth), 2.3–2.8 mm wide, with prominent reticulate venation.

Thesium procerum is abundant and widespread and is therefore appropriately classified as Least Concern (IUCN Standards and Petitions Subcommittee, 2017). Additional specimens examined South Africa. LIMPOPO: 2428 (Nylstroom): 10 mi [16.1 km] N of town [Nylstroom] (–CB), 03 Oct 1938, Hafström and Acocks 463 (PRE). 2429 (Zebediela): Makapan (−AA), 30 Apr 1947, Maguire 621 (J); Potgietersrus [Mokopane] (−AA), Dec 1928, Thode A1768 (PRE). NORTH WEST: 2526 (Zeerust): Zeerust (–CA), 15 Oct 1969, Wells 4052 (PRE). 2527 (Rustenburg): Magaliesberg, Silkaatsnek (–DB), 25 Nov 1951, Repton 3887 (PRE). GAUTENG: 2528 (Pretoria): N helling [slope] Magaliesberg ±3 myl [4.8 km] W van Wonderboompoort (–CA), 23 Nov 1928, − 1279 (PRU); Brummeria, Pretoria National Botanical Gardens (–CB), 02 Oct 1963, Stauffer and Mauve s.n. (BOL); National Botanical Garden, Pretoria, next to road on NE side of grassland (–CB), 18 Oct 2016, Le Roux 180 (PRE); Cullinan District, Little Eden Resort (−DA), 21 Nov 2013, Van Greuning 939.1 (PRU); Doornkraal (−DA), 27 Mar 1960, Strey 3266 (BOL, K, PRE); Premier Mine (−DA), Feb 1924, Rogers 25,340 (J). 2627 (Potchefstroom): Carletonville, Anglo-Ashanti West Wits Goldmines mineral rights area (−AD), 06 Nov 2006, de Castro 1100 (PRE). 2628 (Johannesburg): Kopjes [hills], Alberton (–AC), 21 Nov 1926, Moss 13,756 (J); 1 mi [1.6 km] N of Heidelberg on main road (−AD), 11 Dec 1946, Codd 2314 (PRE); Heidelberg (−AD), May 1913, Bonsma 12,776 (PRE), 26 Nov 1909, Leendertz 2546 (PRE), Jan 1912, Thode 4814 (PRE); Heidelberg Kloof (−AD), 01 Feb 1953, Repton 4022 (PRE); 03 Jan 1953, Mogg

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20,486 (PRE); Kopje [hill], kloof, Heidelberg (−AD), 10 Nov 1925, Ottley 2264 (J); Suikerbosrand, Bosfontein (−AD), 07 Apr 1972, Bredenkamp 809 (PRE, PRU). MPUMALANGA: 2529 (Witbank): Loskopdam (−AD), Feb 1978, Visser 253 (PRU); Middelburg, Doornkop 273 J.S. “Ghost Rocks” E of Eerstekamp (–CB), 25 Jan 1968, Du Plessis 270 (PRU); 29 Oct 1968, Du Plessis 976 (PRE, PRU); Olifantsriver (–CB), 02 Apr 1922, Rudatis 2614 (PRE);. 2530 (Lydenburg): Rietvlei municipal farm, 2 mi [3.2 km] off Uitkyk road from Nelspruit (–BD), 15 Sep 1970, Buitendag s.n. (NBG). 8. T. resedoides A.W.Hill in Bull. Misc. Inform. Kew 6: 187 (1910); Baker and A.W.Hill in Dyer, Fl. Trop. Afr. 6(1): 419 (1911); A.W.Hill in Dyer, Fl. Cap. 5(2): 181 (1925); N.E.Br. in Burtt Davy, Man. Pl. Transvaal 2: 460 (1932); Retief and P.P.J.Herman in Plants of the northern provinces of South Africa: 599 (1997); Hilliard in Fl. Zambes. 9(3): 235 (2006); Retief and N.L.Mey. in Plants of the Free State: 752 (2017). Thesium welwitschii sensu Baum, in Kunene-Sambesi-Exped.: 230 (1903), non Hiern. (1896). Type: Angola (1617): Rechtes Ufer des Okachitanda [right bank of the Okachitanda (Chitanda/Cubango river)], 25 Sep 1899, Baum 152 (K, holo.!; B – image!, BM!, BR – image!, E – image!, iso.). T. burkei A.W.Hill in Bull. Misc. Inform. Kew 1: 24 (1915); A.W.Hill in Dyer, Fl. Cap. 5(2): 180 (1925); N.E.Br. in Burtt Davy, Man. Pl. Transvaal 2: 460 (1932); Retief and P.P.J.Herman in Plants of the northern provinces of South Africa: 597 (1997). Type: South Africa, North West, Rustenburg (2527): Magaliesberg (–DC), Burke s.n. (K, lecto.!, designated by Brown: 461 (1932)). T. junodii A.W.Hill in Bull. Misc. Inform. Kew 1: 33 (1915), syn. nov.; A.W.Hill in Dyer, Fl. Cap. 5(2): 182 (1925); N.E.Br. in Burtt Davy, Man. Pl. Transvaal 2: 461 (1932); Retief and P.P.J.Herman in Plants of the northern provinces of South Africa: 598 (1997). Type: South Africa, Limpopo, Pilgrim's Rest (2430): Shilouvane [Shilovane] (–AB), Junod 1301 (K, lecto.!, designated here). Other original material: without precise locality, Wahlberg s.n. (K, syn.!; S, syn. – image!). [Note: Junod 1301 was chosen as the lectotype of T. junodii as the specimen is signed and annotated by A.W.Hill and the Wahlberg collection from Kew consists of only half a flower]. T. dumale N.E.Br. in Burtt Davy, Man. Pl. Transvaal 2: 461 (1932). Type: South Africa, North West, Vryburg (2426): farm Concordia (−DD), Combrinck H6985 (PRE, holo.!; K!, iso.). T. mossii N.E.Br. in Burtt Davy, Man. Pl. Transvaal 2: 460 (1932), syn. nov.; Retief and P.P.J.Herman in Plants of the northern provinces of South Africa: 598 (1997). Type: South Africa, Limpopo, Messina (2230): Messina (–AC), Nov 1916, Moss and Rogers 60 (PRE, holo.!). Rhizomatous suffrutex, 0.1–0.4 m tall, vegetative scales present on rhizome and lower parts of stems, stems 2 to 14(23), arising from rhizome at intervals, erect or suberect, compact, branched, sulcate to angular distally through decurrent leaves, terete below, brown to green, usually sparsely leafy, occasionally moderately leafy (5–12(18) leaves per 50 mm at middle of stem). Leaves spreading, often recurved, linear, 4.5–22.5(26.0) × 0.3–2.3 mm, apex acuminate and usually cartilaginous, midrib often raised on both surfaces, margins entire. Flowers usually solitary in bract axils, arranged in 5 to 16-flowered monotelic, racemose inflorescences sometimes accompanied by simple 3-flowered dichasial cymes, or very rarely 2 to 3-flowered monochasial cymes; pedicels (0.0)0.5–3.0 mm long, peduncles 0.5–7.0(22.0) mm long. Bracts linear-lanceolate, 2.0–9.0 × 0.2–1.0 mm, apex acuminate, margins entire, fused to entire pedicel/peduncle; bracteoles 1.7–6.5 × 0.2– 0.4(1.0) mm. Perianth 2.5–3.3(5.0) mm long, elongate receptacle usually absent, “glands” often visible on outside; lobes narrowly triangular, 1.1–1.5 × 0.4–0.9 mm, apex slightly hooded, with dense apical beard. Stamens inserted at base of tepals; filaments 0.2–0.4 mm long; anthers 0.4–0.7 mm long. Style 0.5–1.1 mm long, stigma ± opposite anthers. Placental column straight. Fruit

sessile, 3.5–7.0 mm long including persistent perianth (2.5–5.0 mm long excluding perianth), 2.0–2.8 mm wide, with prominent reticulate venation. Distribution and ecology Thesium resedoides is widespread throughout Angola, Namibia, Botswana, Mozambique, Swaziland and South Africa (Hilliard, 2006), where it is found in the eastern parts of the Northern Cape, North West, Limpopo, northern Gauteng, eastern Mpumalanga and northern KwaZulu-Natal (Fig. 7H). This species is restricted to the savanna biome and occurs mainly in grassland patches in bushveld and thornveld areas, as well as open woodlands and grasslands at elevations between 50 and 1676 m a.s.l., mainly on rocky soils. Flowering time is between September and February. Diagnostic characters Thesium resedoides is characterised by much-branched stems that grow at more or less 45° angles (Fig. 5D), the lower parts of the stems often terete, and small flowers 2.5–3.3 mm long. Although T. resedoides occurs mainly in the savanna biome it may be confused with the grassland species T. goetzeanum where the range of these two species overlap in northern KwaZulu-Natal, eastern Mpumalanga, Limpopo, northern Gauteng and the western part of the North West province (Fig. 4). Thesium goetzeanum has sparsely branched, parallel, sulcate stems (Fig. 5A), and larger flowers 3.0–4.5 mm long. In addition, the maximum elevation that T. resedoides has been found at is 1676 m a.s.l., where T. goetzeanum has been found up to 3000 m a.s.l. Regarding synonymy, Hill (1915) described T. junodii based on its slender habit, linear and curved leaves, simple racemose inflorescences and conspicuous external perianth “glands”. However, T. resedoides is polymorphic in growth form and can appear slender, and no differences were observed between the leaves and inflorescences of these two species. The external perianth “glands” of T. resedoides furthermore vary from absent to prominent. In the absence of other distinguishing characters these two species cannot be separated. Brown (1932) described T. mossii as having short flower bearing branches with 2 to 5 flowers each. The type of T. mossii appears to be a young specimen of T. resedoides and has branches with up to 6 flowers, which falls within the known range of T. resedoides (5–16 flowers). Conservation status Thesium resedoides is abundant and widespread and is therefore appropriately classified as Least Concern (IUCN Standards and Petitions Subcommittee, 2017). The taxa T. junodii A.W.Hill and T. mossii N.E.Br., currently listed as data deficient due to taxonomic problems (Raimondo et al., 2009), are now treated as synonyms of T. resedoides. Additional specimens examined South Africa. LIMPOPO: 2231 (Pafuri): Punda Maria (–CA), 21 Jan 1953, Van der Schijff 1898 (PRE). 2329 (Pietersburg): Between Boyne and Haenertsburg (−DD), 01 Feb 1982, Brenan 14,920 (PRE). 2428 (Nylstroom): Warmbaths [Bela-Bela] (–CD), 30 Sep 1908, Leendertz 1335 (PRE), 30 Sep 1908, Leendertz 1353 (J, K, PRE); Warmbaths [BelaBela], Waterberg (–CD), Nov 1918, Rogers 22,146 (K). NORTH WEST: 2524 (Vergeleë): Erinn farm (−DD), 13 Feb 1982, Gubb 242/86 (PRE). 2527 (Rustenburg): Saulspoort, Kwa-Ramogo on mountain side (−AA), 28 Nov 1977, Germishuizen 490 (K, PRE); Bophutatswana, Pilanesberg National Park, new road between main road and Mankwe loop, ± 1.0–1.5 km from main road (–AC), 06 Jan 1991, Glen 2480 (J, PRE); Magaliesberg (–DC), Burke s.n. (K). 2624 (Vryburg): Vryburg (–DC), Feb 1924, Henrici 27 (PRE). 2723 (Kuruman): Hermitage farm (–AB), 01 Mar 1982, Gubb 264/41 (PRE);

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Boscobel farm, top of Asbestos hills (–BA), 03 Mar 1982, Gubb 268/82 (PRE). 2725 (Bloemhof): Makwassie, Wolmaransstad (–BD), 12 Mar 1969, Morris and Boucher 450 (PRE); Slopes above pan, farm Witgatboom (–CB), 28 Nov 2007, Burgoyne 10,971 (PRE). GAUTENG: 2528 (Pretoria): 25 mi [40 km] N of town [Pretoria] (−AD), 01 Oct 1938, Acocks 460 (PRE); near Pretoria (–CB), May 1922, Rogers s.n. (K); Roodeplaat Research Station (–CB), 02 Dec 1973, Clarke 559 (PRE); Donkerhoek, 22 mi [35 km] from BRI on Pretoria-Witbank freeway (–CD), 09 Nov 1987, Crosby 460 (PRE). MPUMALANGA: 2531 (Komatipoort): Komatipoort (–BD), Aug 1886, Bolus 9765 (PRE), 17 Dec 1897, Schlechter 11,803 (PRE); Lebomboberge, Krokodilbrug [Lebombo mountains, Crocodile Bridge] (–BD), 09 Nov 1954, Van der Schijff 3981 (PRE). KWAZULU-NATAL: 2631 (Mbabane): Mhlumi Sugar Estates, Thsaneni (–BB), Oct 1977, Visser 286 (K, PRE), Visser 287 (K, NBG, PRE). 2632 (Bela Vista): Ndumu store (–CD), 18 Oct 1973, Hilliard and Burtt 6875 (PRE). 2731 (Louwsburg): Pongolo [Pongola] (–BC), 29 Nov 1957, King s.n. (NH, PRE). 2732 (Ubombo): 3 mi [4.8 km] E of Pongola River on road to Maputo (–AB), 21 Nov 1969, Moll 4608 (K, PRE); Mkuze flats E of Jozini (−AD), 14 Feb 1976, Brenan 14,256, 14,257 (K, PRE); on road to Ubombo from Sodwana Bay (−AD), 30 Aug 1978, Smook 1311 (PRE); Mkuze Game Reserve (–CA), 29 Jan 1982, Goetghebeur 4390 (PRE); near gates of Mkuze Game Reserve (– CA), 21 Feb 1982, Reid 507 (PRE); Mosi State Forest, 6 km S of Mansibomvu (−DA), 24 Sep 1987, Groenewald 23 (PRE, NH). 2831 (Nkandla): Umfolozi Game Reserve (–BD), 22 Nov 1959, Ward 3293 (K, PRE); vicinity of Mpila rest camp, Umfolozi Game Reserve (–BD), 06 Jan 1986, Pienaar 858 (K, PRE). 2930 (Pietermaritzburg): Scottsville (–CB), 01 Oct 1939, Fairall 47 (NBG). NORTHERN CAPE: 2723 (Kuruman): 3 mi [4.8 km] N by E of Kuruman (−AD), 30 Nov 1957, Leistner 981 (PRE). 2824 (Kimberley): Cristaalfontein 17 Kl (–AB), 17 Dec 1936, Acocks 1493 (K, PRE); Pniel (–CB), Jan 1937, Acocks 1559 (K, PRE); Kimberley (–DB), Marloth s.n. (PRE). Swaziland. 2531 (Komatipoort): Pigg's Peak (–CD), 24 Mar 1959, Compton 28,722 (PRE); Sihoya (–DC), 30 Nov 1964, Dicks s.n. (PRE); 13 Jan 1965, Compton s.n. (K, PRE). 2631 (Mbabane): Mbuluzi Nature Reserve, 300 m SE of Maphiveni (−AA), 29 Dec 1985, Culverwell 1429 (PRE); Ngwenya mountains, Bomvu Ridge (−AA), 28 Feb 1957, Compton 26,706 (PRE); Bahlakane bridge, Siza Ranch, Nonyane 924 (–AB), 11 Dec 1999, De Castro and Brits 285 (PRE), 17 Dec 1999, De Castro and Brits 419 (PRE); hills W of Mbabane (–AC), 30 Jan 1956, Compton 25,507 (PRE); St. Josephs (−AD), 12 Dec 1963, Karsten s.n. (PRE); Ingwavuma Poort (–BB), 13 Nov 1959, Compton 29,446 (K, NBG, NH, PRE); Ranches, Stegi (–BD), 08 Sep 1957, Compton 27,028 (PRE, NBG); Red Tiger Ranch, Manzini (–CB), 31 Oct 1961, Compton 30,955 (PRE); Sipofaneni (−DA), 14 Nov 1956, Compton 26,302 (PRE, NH, NBG); Big Bend (−DD), 18 Nov 1960, Compton 30,283 (PRE, NBG). 9. T. vahrmeijeri Brenan in Kew Bull. 33(3): 396 (1979); Hilliard in Fl. Zambes. 9(3): 239 (2006). Type: South Africa, KwaZulu-Natal, Ubombo (2732): Lake Sebayi, Umdoni veld near lake shore (–BC), 13 Feb 1976, Brenan and Vahrmeijer 14,221 (K, holo.!; PRE!, iso.). Annual herb, 0.1–0.3 m tall, with slender, non-woody branched root system, vegetative scales absent from roots and lower parts of stems, stems 1 to 7 from rootstock, sub-erect or spreading with lower often decumbent, slender, branched, sulcate distally through decurrent leaves, terete below, green, moderately leafy (8–16 leaves per 50 mm at middle of stem). Leaves spreading, often recurved, linear, 5.0–27.0 × 0.3–0.9 mm, apex acute-acuminate and usually not cartilaginous, midrib raised on both surfaces, margins entire. Flowers solitary in bract axils, arranged in sparse 3 to 8-flowered monotelic racemose inflorescences; pedicels 0.0–2.0 mm long. Bracts linear-lanceolate, 3.7–6.0 × 0.3–0.7 mm, apex acuminate, margins entire, fused to entire pedicel; bracteoles 2.0–3.5 × 0.2–0.3 mm. Perianth 2.5–3.0 mm long, with elongate receptacle,

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“glands” very rarely visible on outside; lobes linear or narrowly triangular, 0.8–1.2 × 0.2–0.5 mm, apex slightly hooded, with dense apical beard. Stamens inserted at base of tepals; filaments 0.2–0.3 mm long; anthers 0.3–0.4 mm long. Style 0.5–0.6 mm long, stigma ± opposite anthers. Placental column straight. Fruit stipitate, 3.0–6.8 mm long including persistent perianth (3.0–5.0 mm long excluding perianth), 1.8–2.5 mm wide, with prominent reticulate venation. Distribution and ecology Thesium vahrmeijeri is found in coastal regions between Inhambane in Mozambique and Mtunzini (KwaZulu-Natal) in South Africa (Fig. 7I) (Hilliard, 2006) at elevations between 10 and 152 m a.s.l. It occurs in wooded grasslands on sandy soils. Flowering time is between August and January. Diagnostic characters Thesium vahrmeijeri is routinely misidentified as T. resedoides but is easily recognised as the only annual herbaceous species in the T. goetzeanum complex. Plants have a slender branched root system (Fig. 1F), lacking vegetative scales on the roots and lower part of the stems, which are slender and often spreading, with stipitate fruits (Fig. 6G). Thesium resedoides is a suffrutex with a thick woody rhizome, with vegetative scales on the roots and lower parts of the stems, robust erect or sub-erect stems, and sessile fruits. Thesium vahrmeijeri is also spatially separated from the rest of the T. goetzeanum complex as its distribution is restricted to coastal regions in northern KwaZulu-Natal at elevations lower than 152 m a.s.l. Conservation status Thesium vahrmeijeri is abundant and widespread and most of its distribution falls within protected areas (IUCN Standards and Petitions Subcommittee, 2017). We therefore suggest that it be classified as Least Concern. Thesium vahrmeijeri was previously listed as data deficient due to taxonomic reasons (Raimondo et al., 2009). Additional specimens examined South Africa. KWAZULU-NATAL: 2632 (Bela Vista): Kosi Bay, 10 km from sea on road to Manguzi (−DD), 13 Oct 1982, Germishuizen 2037 (PRE); Kosi Estuary (−DD), 09 May 1965, Vahrmeijer and Tölken 895 (PRE). 2732 (Ubombo): Kosi Bay, Coastal Forest Reserve, W of Ku-Schengeza Pan (–BB), 22 Oct 1994, Van Wyk 12,426 (PRE, PRU); I.D.C. rice project site, ± 2 km from turnoff to Phelendaba on Mbazwana road (–BC), 03 Dec 1985, Germishuizen 3562 (PRE), 04 Dec 1985, Germishuizen 3629 (PRE); near Manzengwenya inspection quarters (–BC), 29 Nov 1969, Moll 4859 (K, PRE); Island Rock, S of viewing tower for forestry (–BD), 29 Aug 1996, Felton and Thornhill 123 (PRE); Mpangazi (−DA), 10 Jan 1964, Strey 5063 (NH, PRE). 2831 (Nkandla): Umhlatuzi Flats, Uqubu Lake area (−DD), 13 Sep 1966, Venter 2553 (PRE). 2832 (Mtubatuba): coastal dunes at Santa Lucia Bay (−AD), 01 May 1958, Jacobsen 1377 (PRE); Cape Vidal (– BA), 27 Jun 1971, Ward 7095 (PRE); Eastern Shores State Forest, near Simbomvini road turn off (–BA), 06 Mar 1985, Nicholas and MacDevette 2154 (K, PRE); 2.5 km van [from] Arboretum, op ou pad na [on old road towards] Empangeni (–CC), 12 Dec 1985, Pienaar 825 (PRE). Acknowledgements The following people and institutions are thanked: Curators and staff members of cited herbaria for assistance during visits, preparation of loans and sharing of knowledge; John Burrows, Bronwynn Egan, Kate and Graham Grieve, Andrew Hankey, Daniel Nickrent, Delia Oosthuizen

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and Barbara Turpin for help in the field; Lize von Staden and Kate Braun for assistance with conservation status assessments; the South African National Biodiversity Institute (SANBI) for financing, hosting and facilitating research for this project, in particular the National Herbarium; Department of Economic development, tourism and environmental affairs Free State province, Ezemvelo KZN Wildlife, Mpumalanga Tourism and Parks Agency, Premier of the Province of Gauteng Nature Conservation for providing collection permits and Karin Behr for assistance with permit applications; the Foundational Biodiversity Information Programme (Small Grant number 104931), the SANBI and the National Research Foundation of South Africa (Grant number 8442) for funding. References Baker, J.G., Hill, A.W., 1911. Order CXX. Santalaceae. In: Thiselton-Dyer, W.T. (Ed.), Flora of Tropical Africa. L. Reeve & Co. LTD, Kent, pp. 411–431. Bhatnagar, S., Agarwal, S., 1961. Morphological and embryological studies in the family Santalaceae. Phytomorphology 11, 273–282. Brenan, J., 1979. Three new species of Thesium (Santalaceae) from South Africa. Kew Bulletin 33, 395–397. Brown, N.E., 1932. Thesium L. In: Burtt-Davy, J. (Ed.), A manual of the flowering plants and ferns of the transvaal with Swaziland, South Africa. Longmans, Green and Co., London, pp. 455–462. Cohn, J., 2004. Effects of slashing and burning on Thesium australe R. Brown (Santalaceae) in coastal grasslands of NSW. Proceedings of the Linnean Society of New South Wales 125, 57–65. De Candolle, A., 1857a. Santalaceae. In: De Candolle, A. (Ed.), Prodromus systematis naturalis, pp. 619–692 Paris. De Candolle, A., 1857b. Espéces nouvelles du genre Thesium présentées à la Société de physique et d'histoire naturelle de Genève dans sa séance du 25 Mai 1857. Ramboz et Schuchardt, Genève, pp. 1–8. Der, J.P., Nickrent, D.L., 2008. A molecular phylogeny of Santalaceae (Santalales). Systematic Botany 33, 107–116. Forest, F., Manning, J.C., 2013. The minor genera Kunkeliella and Thesidium included in Thesium. Bothalia 43, 214–216. Gamoun, M., 2014. Grazing intensity effects on the vegetation in desert rangelands of southern Tunisia. Journal of Arid Land 6, 324–333. Germishuizen, G., Meyer, N., Steenkamp, Y., Keith, M., 2006. A checklist of South African plants. South African botanical diversity network report no. 41. SABONET, Pretoria, pp. 767–772. Hendrych, R., 1972. The natural history and systematic of the genus Thesium L. Acta Universitatis Carolinae - Biologica 293–358.

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