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Studies in Cyperaceae in southern Africa. 20: Changed status of Schoenoplectus corymbosus var. brachyceras and report of hybrids
S.Afr.J.Bot., 1992, 58(6): 530 - 532
530
Studies in Cyperaceae in southern Africa. 20: Changed status of Schoenoplectus corymbosus var. brachyceras and report of hybrids J. Browning UN/FRO Research Unit for Plant Growth and Development, Department of Botany, University of Natal, P.O. Box 375, Pietermaritzburg, 3200 Republic of South Africa Received 8 May 1992; revised 31 July 1992
1. Schoenoplectus corymbosus (Roth ex Roem. & Schult.) J. Raynal var. brachyceras (A. Rich.) K. Lye is reverted to specific status as S. brachyceras (A. Rich.) K. Lye. 2. Suspected natural hybridization between Schoenoplectus brachyceras and S. decipiens (Nees) J. Raynal is reported. Variants (interpreted as introgressives) occurred together with both putative parents under vlei conditions near Wakkerstroom, Transvaal, South Africa. Significant morphological features that support this hybridization are described and illustrated. 1. Schoenoplectus corymbosus (Roth ex Roem . & Schult.) J. Raynal var. brachyceras (A. Rich.) K. Lye word teruggeplaas na spesifieke status as S. brachyceras (A. Rich.) K. Lye. 2. Die waarskynlikheid van natuurlike kruising tussen Schoenoplectus brachyceras en S. decipiens (Nees) J. Raynal word gedokumenteer. Variante (ge·interpreteer as introgressiewes) is tesame met beide waarskynlike ouers onder vleitoestande naby Wakkerstroom, Transvaal, Suid-Afrika, gevind. Betekenisvolle karaktertrekke wat sodanige kruising ondersteun, word beskryf en ge·illustreer. Keywords: Schoenoplectus, taxonomy, hybridization, southern Africa.
1. Reversion to specific status for Schoenoplectus corymbosus var. brachyceras Study of Schoenoplectus (Reichenbach) Palla in southern Africa has revealed differences between S. corymbosus (Roth ex Roem. & Schult.) J. Raynal var. corymbosus and var. brachyceras (A. Rich.) K. Lye that are as well marked as the criteria that differentiate other species within the genus, for example S. muriculatus (Kuekenthal) J. Browning and S. muricinux (C.B . Cl.) J. Raynal; S. confusus (N.E. Br.) K. Lye and S. muricinux (Browning 1991a, 1991b); S. litoralis (Schrader) Palla and S. lacustris (L.) Palla (Browning, in prep.). The epithet 'brachyceras' within Scirpus L. dates from 1850 when Richard (1850) established Schimper 288 [Ethiopia (Abyssinia) Adoam (K!)] as the type of a species. Subsequently, Lye (1971) transferred Scirpus brachyceras A. Rich. to Schoenoplectus at specific level, but later (Lye 1983) reduced it to varietal status under S. corymbosus. Raynal (1976) did not differentiate Schoenoplectus brachyceras from S. corymbosus. For consistency, the proposal is now made that S. corymbosus var. brachyceras revert to specific level as Schoenoplectus brachyceras (A. Rich.) K. Lye.
2. Suspected natural hybridization in Schoenoplectus Introduction Browning (1990, 1991b) recircumscribed Schoenoplectus decipiens (Nees) J. Raynal and S. corymbosus (Roth ex Roem. & Schult.) J. Raynal var. brachyceras (A. Rich.) K. Lye - the latter now reinstated as S. brachyceras (A. Rich.) K. Lye. There is close morphological relationship between these species. In certain parts of their distributional ranges they are sympatric, for example Wakkerstroom, Transvaal.In a large vlei near the town, S. decipiens grew in
wet grassland and 'sedge meadow', while S. brachyceras was present further into the vlei in slightly deeper, more open standing water covering a dense 'root mat' of organic material (here called 'sedge marsh' in contrast to 'sedge meadow' where shallow water grading to wet mud is present but hidden by a continuous vegetational cover of sedges with occasional grasses intermingled). Collection of specimens along a transect through the vlei revealed the presence of both species as well as variants that fitted neither species precisely, but which exhibited features of both. Some of the variants were more or less intermediate morphologically; others were closer to one or other of the species named. Study suggests that these variants are products of gene exchange (interspecific hybridization with the establishment of intermediates that then may backcross with either parent, or maintain themselves as clones reproducing vegetatively). They are here interpreted as introgressives, with S. brachyceras and S. decipiens the putative parents. Supportive evidence In Table 1 (based on Browning 1990, 1991b) are summarized the significant features of the putative parents. Distinction depends upon several features (each exhibiting some range of variation) being considered collectively. These criteria are: shape and length of overtopping inflorescence bract; inflorescence branching, or its lack; plant height; culm width below the inflorescence; anther crest length and ornamentation (Figure 1 A,a; C,c). Glume dimensions and apex, style branch length, anther length, achene dimensions and surface sculpturing, even when considered collectively, do not reliably differentiate the putative parents. Morphological relationship is therefore close. However, the growing plants have a different facies, S. brachyceras being the more robust and taller, but usually the less markedly tufted These differences are correlated with different habitat preferences (Figure 2).
S.Afr.J.Bot.,1992,58(6)
531
Table 1 Qualitative and quantitative parameters representative of Schoenoplectus brachyceras and S. decipienS' S. brachyceras
S. decipiens
Plant height Overtopping bract length Culm width below inflorescence Inflorescence
300 - 2400 15 - 35 Cboat-shaped') 4 - 10 Pseudolatera! anthela with 1 - 10 branches
Glume dimensions (including mucro) Anther length (including crest) Anther crest length Style branch length Achene dimensions Achene surface
3.0 - 4.0 X 2.0 - 2.5 1.5 - 2.3 0.38 - 0.5 1.5 - 3.0 1.1 - 1.7 X 0.9 - 1.3 Smooth to rugulose
80 - 800 20 - 90 (narrowly tapering) 1.5 - 4 Pseudolatera! head, occasionally an anthela with 1 - 3 branches 2.8 - 4.5 X 1.5 - 2.4 1.0-1.75 0.1 - 0.18 1.7 - 3.2 1.3 - 1.9 X 0.9 - 1.3 Smooth to rugulose
• All measurements are given in millimetres.
I A
c
B
a
b
c
Figure 1 Inflorescences and anther crests . A,a. Schoenopleclus decipiens, Kolze 176; B,b. Introgressive, Kolze 180; ceras. Kolze 184. Scale bars for inflorescences: 10 mm; for anther crests: 200 fJ..m.
C,c, S. brachy-
S.-Afr.Tydsla.Plantk., 1992,58(6)
532
A
S. decipiens
B
c
Introgressives
S. brachyceras
References BROWNING, J. 1990. Studies in Cyperaceae in southern Africa. 16: A re-examination of Schoenoplectus paludicola, Sch. decipiens and Sch. pulchellus. S. Afr. 1. Bot. 56: 16 - 28. BROWNING, J. 1991a. Studies in Cyperaceae in southern Africa. 17: An examination of Schoenoplectus muricinux (C .B. CI.) J. Raynal sensu lato. S. Afr. 1. Bot. 57: 249 - 259.
Kotze 175--179
Kotze 180-183
Kotze 184
Figure 2 Diagrammatic representation of vlei transect. A.'Wet grassland'; B, 'sedge meadow'; C, 'sedge marsh'; D, approximate water level at time of collection; E, 'root mat' .
Specimens studied -2730 (Vryheid): vlei near Wakkerstroom (-AC), Kolze 175 184 inclusive (all NU). NOTE: KOlze 175 -179 are S. decipiens (Figure 1A,a) Kolze 184 is S. brachyceras (Figure 1 C,c) Kolze 180 - 183 are intTogressives (Figure 2) .
Nomenclature The introgressives (intermediate putative hybrids) should be known by the formula Schoenoplectus decipiens X S. brachyceras.
BROWNING, J. 1991b. Studies in Cyperaceae in southern Africa. 18: A re-appraisal of Schoenoplectus corymbosus. S. Afr. 1. Bot. 57: 335 - 343. BROWNING, J. (in prep.) Studies in Cyperaceae in southern Africa. Schoenoplectus litoralis, S. lacustris and S. triquetrus. LYE, K.A. 1971. Studies in African Cyperaceae. 3. A new species of Schoenoplectus and some new combinations. Bot. Notiser 124: 287 - 291. LYE, K.A. 1983. Studies in African Cyperaceae 27. Miscellaneous new taxa and combinations. Nordic 1. Bot. 3(2): 242. RA YNAL, J. 1976. Schoenoplectus. In: Catalogue des Plantes Vasculaires du Niger. Etude Botanique 3, eds. B.P. Fabregues & J.P. Lebrun, pp. 342 - 344. Institut d'Elevage et de Medicine Veterinaire des Pays Tropicaux, AlfOTt, France. RICHARD, A. 1850. Tentamen Florae Abyssinicae 2: Parisi is, 518 pp.
530
Studies in Cyperaceae in southern Africa. 20: Changed status of Schoenoplectus corymbosus var. brachyceras and report of hybrids J. Browning UN/FRO Research Unit for Plant Growth and Development, Department of Botany, University of Natal, P.O. Box 375, Pietermaritzburg, 3200 Republic of South Africa Received 8 May 1992; revised 31 July 1992
1. Schoenoplectus corymbosus (Roth ex Roem. & Schult.) J. Raynal var. brachyceras (A. Rich.) K. Lye is reverted to specific status as S. brachyceras (A. Rich.) K. Lye. 2. Suspected natural hybridization between Schoenoplectus brachyceras and S. decipiens (Nees) J. Raynal is reported. Variants (interpreted as introgressives) occurred together with both putative parents under vlei conditions near Wakkerstroom, Transvaal, South Africa. Significant morphological features that support this hybridization are described and illustrated. 1. Schoenoplectus corymbosus (Roth ex Roem . & Schult.) J. Raynal var. brachyceras (A. Rich.) K. Lye word teruggeplaas na spesifieke status as S. brachyceras (A. Rich.) K. Lye. 2. Die waarskynlikheid van natuurlike kruising tussen Schoenoplectus brachyceras en S. decipiens (Nees) J. Raynal word gedokumenteer. Variante (ge·interpreteer as introgressiewes) is tesame met beide waarskynlike ouers onder vleitoestande naby Wakkerstroom, Transvaal, Suid-Afrika, gevind. Betekenisvolle karaktertrekke wat sodanige kruising ondersteun, word beskryf en ge·illustreer. Keywords: Schoenoplectus, taxonomy, hybridization, southern Africa.
1. Reversion to specific status for Schoenoplectus corymbosus var. brachyceras Study of Schoenoplectus (Reichenbach) Palla in southern Africa has revealed differences between S. corymbosus (Roth ex Roem. & Schult.) J. Raynal var. corymbosus and var. brachyceras (A. Rich.) K. Lye that are as well marked as the criteria that differentiate other species within the genus, for example S. muriculatus (Kuekenthal) J. Browning and S. muricinux (C.B . Cl.) J. Raynal; S. confusus (N.E. Br.) K. Lye and S. muricinux (Browning 1991a, 1991b); S. litoralis (Schrader) Palla and S. lacustris (L.) Palla (Browning, in prep.). The epithet 'brachyceras' within Scirpus L. dates from 1850 when Richard (1850) established Schimper 288 [Ethiopia (Abyssinia) Adoam (K!)] as the type of a species. Subsequently, Lye (1971) transferred Scirpus brachyceras A. Rich. to Schoenoplectus at specific level, but later (Lye 1983) reduced it to varietal status under S. corymbosus. Raynal (1976) did not differentiate Schoenoplectus brachyceras from S. corymbosus. For consistency, the proposal is now made that S. corymbosus var. brachyceras revert to specific level as Schoenoplectus brachyceras (A. Rich.) K. Lye.
2. Suspected natural hybridization in Schoenoplectus Introduction Browning (1990, 1991b) recircumscribed Schoenoplectus decipiens (Nees) J. Raynal and S. corymbosus (Roth ex Roem. & Schult.) J. Raynal var. brachyceras (A. Rich.) K. Lye - the latter now reinstated as S. brachyceras (A. Rich.) K. Lye. There is close morphological relationship between these species. In certain parts of their distributional ranges they are sympatric, for example Wakkerstroom, Transvaal.In a large vlei near the town, S. decipiens grew in
wet grassland and 'sedge meadow', while S. brachyceras was present further into the vlei in slightly deeper, more open standing water covering a dense 'root mat' of organic material (here called 'sedge marsh' in contrast to 'sedge meadow' where shallow water grading to wet mud is present but hidden by a continuous vegetational cover of sedges with occasional grasses intermingled). Collection of specimens along a transect through the vlei revealed the presence of both species as well as variants that fitted neither species precisely, but which exhibited features of both. Some of the variants were more or less intermediate morphologically; others were closer to one or other of the species named. Study suggests that these variants are products of gene exchange (interspecific hybridization with the establishment of intermediates that then may backcross with either parent, or maintain themselves as clones reproducing vegetatively). They are here interpreted as introgressives, with S. brachyceras and S. decipiens the putative parents. Supportive evidence In Table 1 (based on Browning 1990, 1991b) are summarized the significant features of the putative parents. Distinction depends upon several features (each exhibiting some range of variation) being considered collectively. These criteria are: shape and length of overtopping inflorescence bract; inflorescence branching, or its lack; plant height; culm width below the inflorescence; anther crest length and ornamentation (Figure 1 A,a; C,c). Glume dimensions and apex, style branch length, anther length, achene dimensions and surface sculpturing, even when considered collectively, do not reliably differentiate the putative parents. Morphological relationship is therefore close. However, the growing plants have a different facies, S. brachyceras being the more robust and taller, but usually the less markedly tufted These differences are correlated with different habitat preferences (Figure 2).
S.Afr.J.Bot.,1992,58(6)
531
Table 1 Qualitative and quantitative parameters representative of Schoenoplectus brachyceras and S. decipienS' S. brachyceras
S. decipiens
Plant height Overtopping bract length Culm width below inflorescence Inflorescence
300 - 2400 15 - 35 Cboat-shaped') 4 - 10 Pseudolatera! anthela with 1 - 10 branches
Glume dimensions (including mucro) Anther length (including crest) Anther crest length Style branch length Achene dimensions Achene surface
3.0 - 4.0 X 2.0 - 2.5 1.5 - 2.3 0.38 - 0.5 1.5 - 3.0 1.1 - 1.7 X 0.9 - 1.3 Smooth to rugulose
80 - 800 20 - 90 (narrowly tapering) 1.5 - 4 Pseudolatera! head, occasionally an anthela with 1 - 3 branches 2.8 - 4.5 X 1.5 - 2.4 1.0-1.75 0.1 - 0.18 1.7 - 3.2 1.3 - 1.9 X 0.9 - 1.3 Smooth to rugulose
• All measurements are given in millimetres.
I A
c
B
a
b
c
Figure 1 Inflorescences and anther crests . A,a. Schoenopleclus decipiens, Kolze 176; B,b. Introgressive, Kolze 180; ceras. Kolze 184. Scale bars for inflorescences: 10 mm; for anther crests: 200 fJ..m.
C,c, S. brachy-
S.-Afr.Tydsla.Plantk., 1992,58(6)
532
A
S. decipiens
B
c
Introgressives
S. brachyceras
References BROWNING, J. 1990. Studies in Cyperaceae in southern Africa. 16: A re-examination of Schoenoplectus paludicola, Sch. decipiens and Sch. pulchellus. S. Afr. 1. Bot. 56: 16 - 28. BROWNING, J. 1991a. Studies in Cyperaceae in southern Africa. 17: An examination of Schoenoplectus muricinux (C .B. CI.) J. Raynal sensu lato. S. Afr. 1. Bot. 57: 249 - 259.
Kotze 175--179
Kotze 180-183
Kotze 184
Figure 2 Diagrammatic representation of vlei transect. A.'Wet grassland'; B, 'sedge meadow'; C, 'sedge marsh'; D, approximate water level at time of collection; E, 'root mat' .
Specimens studied -2730 (Vryheid): vlei near Wakkerstroom (-AC), Kolze 175 184 inclusive (all NU). NOTE: KOlze 175 -179 are S. decipiens (Figure 1A,a) Kolze 184 is S. brachyceras (Figure 1 C,c) Kolze 180 - 183 are intTogressives (Figure 2) .
Nomenclature The introgressives (intermediate putative hybrids) should be known by the formula Schoenoplectus decipiens X S. brachyceras.
BROWNING, J. 1991b. Studies in Cyperaceae in southern Africa. 18: A re-appraisal of Schoenoplectus corymbosus. S. Afr. 1. Bot. 57: 335 - 343. BROWNING, J. (in prep.) Studies in Cyperaceae in southern Africa. Schoenoplectus litoralis, S. lacustris and S. triquetrus. LYE, K.A. 1971. Studies in African Cyperaceae. 3. A new species of Schoenoplectus and some new combinations. Bot. Notiser 124: 287 - 291. LYE, K.A. 1983. Studies in African Cyperaceae 27. Miscellaneous new taxa and combinations. Nordic 1. Bot. 3(2): 242. RA YNAL, J. 1976. Schoenoplectus. In: Catalogue des Plantes Vasculaires du Niger. Etude Botanique 3, eds. B.P. Fabregues & J.P. Lebrun, pp. 342 - 344. Institut d'Elevage et de Medicine Veterinaire des Pays Tropicaux, AlfOTt, France. RICHARD, A. 1850. Tentamen Florae Abyssinicae 2: Parisi is, 518 pp.