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Studies in Cyperaceae in southern Africa 39: Cyperus articulatus L. and Cyperus corymbosus Rottb.
South African Journal of Botany 72 (2006) 147 – 149 www.elsevier.com/locate/sajb
Studies in Cyperaceae in southern Africa 39: Cyperus articulatus L. and Cyperus corymbosus Rottb. K.D. Gordon-Gray a,*, C.J. Ward b, T.J. Edwards a a
School of Botany and Zoology, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa b P.O. Box 30501, Mayville 4058, South Africa Received 23 July 2004; accepted 14 June 2005
Abstract Cyperus articulatus L. and Cyperus corymbosus Rottb. were studied in southern Africa and were found to be synonymous. The latter bears laminae, has longer bracts and frequently has less septate culms than the former but these differences are phenotypic. Phenotypes formerly referred to C. corymbosus are generally rare and scattered, occupying the drier fringing zones of populations. A map of the distributional range of C. articulatus in southern Africa is provided, along with an illustration of the Fcorymbosus_ phenotype. D 2005 SAAB. Published by Elsevier B.V. All rights reserved. Keywords: Cyperus articulatus; Cyperus corymbosus; Southern Africa
Cyperus articulatus L. and Cyperus corymbosus Rottb., two tropical, perennial, rhizomatous, helophytic hydrophytes had been considered specifically distinct until Tucker (1994), after an extensive survey of Mexican, South American and Old World specimens, found he could not substantiate accepted character differences. Consequently he treated C. corymbosus as a synonym of C. articulatus. Study in southern Africa has supported Tucker’s treatment. We propose that the former is a laminate form with longer bracts and frequently less septatenoded culms. Commonly sympatric, the two entities are distributed widely; C. corymbosus is rare and scattered within or adjacent to more extensive stands of C. articulatus. Cyperus articulatus L. Sp. pl. 1: 44 (1753), Kunth: 53 (1837), Steudel: 30 (1855), Boeck.: 274 (1869/70), C.B.Clarke: 356 (1901/02), Ku¨ kenthal: 77 (1935), Ayers: 1 – 104 (1946), R.W.Haines and Lye: 183 (1983), Tucker: 95 (1994). Lectotype: Sloane, Voy. Jamaica Nat. His. 1: 121, t, 81, Figure 1 (1707). Cyperus corymbosus Rottb. Descr. pl. rar. 19 (1772); C.B.Clarke: 554 (1894), C.B.Clarke: 181 (1897/98), C.B.Clarke: 357 (1901/02), Ku¨kenthal.: 80 (1935), R.W.Haines and Lye: 183 (1983). Type: Suriname, Rolander s.n. (holo., Herb. Rottb. C.). * Corresponding author. E-mail address: [email protected] (K.D. Gordon-Gray).
C. articulatus often occurs in almost pure stands in tropical and warm temperate localities that provide permanent water. It is distinguished by its robust, leafless culms up to 1600 8 mm that are septate-noded and solid-pithed. In life the nodes are not always clearly defined externally but may be detected by gentle finger pressure or longitudinal sectioning. On drying, with shrinkage of pith, the septa stand out markedly. Bracts of the brown, branched, terminal inflorescences are short (5– 9 mm), stiff and sharp and never exceed primary ray length. The subterranean, curved stoloniferous rhizomes are scale-covered when young and terminate, at intervals, in erect, emergent culms. Corm development at the rhizome joints is not usually evident apart from occasional slight enlargements and we found no reference to corm production in the literature. In areas with seasonal climate, fluctuating water levels and greater competition, the plant facies is modified. Culms remain tall, but are slender with fewer septa. Occasionally short, inconspicuous leaf blades terminate the exposed lower leaf sheaths. Bracts are longer (20 –36 mm), becoming leaf-like, but seldom exceed the inflorescence (Fig. 1). C. corymbosus exhibits a close morphological relationship with this less robust expression of C. articulatus. Accepted differences between the two species have been based upon, for C. corymbosus, culms 1- or 2-bladed, bracts leaf-like, culm septa sparse or absent (Clarke, 1901/02; Ku¨kenthal, 1935;
0254-6299/$ - see front matter D 2005 SAAB. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.sajb.2005.06.004
148
K.D. Gordon-Gray et al. / South African Journal of Botany 72 (2006) 147 – 149
Fig. 1. Cyperus articulatus (corymbosus form): whole plant showing one leaf blade drying off. Culm articulations are not well defined (Ward 14828).
Ayers, 1946). Tucker (1994) was unable to substantiate these character differences in a study of Fsome 400 Old World and South American collections labeled as one or other of the species_. He therefore treated C. corymbosus and C. articulatus as synonymous. Metcalfe (1971) examined culms and rhizomes of C. articulatus from Tanzania and cited features of C. corymbosus
extracted from earlier literature without determining any significant anatomical divergence. However, this is a limited assessment requiring confirmation. Synonymy is further supported by distribution. C. articulatus, except for Malaysia, is common pantropically; C. corymbosus is reported from numerous localities within, or fringing the range of C. articulatus but is rare. The only exception to this pattern known to us is in Sri Lanka (Ceylon) where Koyama (1985) reported the apparent replacement of C. articulatus by C. corymbosus over a century. He commented after describing C. articulatus—FIt is rather interesting that this species has never been collected since Trimen’s time_ (c. 1888). Such a change could be the result of gradual modification of habitat, perhaps in conjunction with herbivory or other consistent mutilation. In southern Africa C. articulatus is well-known and widely represented in fresh, or slightly saline, mostly moving water of estuaries, river banks, lakes and wet grassland from sea level to about 1065m altitude (Fig. 2). It is reported from northern Namibia including Caprivi, Botswana, Swaziland and from the Limpopo, Mpumalanga and KwaZuluNatal (Archer, 2003; Retief and Herman, 1997) and the Eastern Cape provinces of South Africa. C. corymbosus is likewise widespread extra territorially, but poorly represented in herbaria and referred to as Frare_ or Funcommon_. Clarke (1897/98) in his treatment of Cyperus for southern Africa, omitted C. articulatus, but did include C. corymbosus, citing only Dre` ge 4406 from FNatal, near the mouth of the Umzimkulu River_ [now Mzimkhulu (Port Shepstone)] and adding FKunth, Enum. ii: 53, partly, i.e. the Dre`ge examples with septations of stems obsolete_: [Note: a fragment of the inflorescence of Dre`ge 4406 is preserved in PRE]. The species has been recollected from Dre`ge’s locality, nearly two centuries later (CJ Ward 14828). Ward (1980) recorded both species from Isipingo, noting the elongated rhizomes, tuberous [sic] only in C. corymbosus. The
Fig. 2. Known distribution of Cyperus articulatus in southern Africa.
K.D. Gordon-Gray et al. / South African Journal of Botany 72 (2006) 147 – 149
presence of well defined underground storage organs in this species (initially termed tubers, but now determined as corms, since they are stems which become hard and woody and are tunicated by frayed leaf sheaths) was a significant distinction from C. articulatus. The presence of corms in an allied species prompted the suggestion (Gordon-Gray, 1995) that C. corymbosus might be a hybrid in South Africa. Subsequent study has dispelled this hypothesis. Our experience is that corm production is induced in habitats influenced by seasonal change, fluctuating water levels and increased competition, and is almost always accompanied by sparse leaf blades and short leaf-like bracts. Such plants occur most commonly during colonization and in areas fringing favourable habitats. Further, we now have evidence of corms in what, on characters of emergent culms, must be named C. articulatus—from both wild collections and cultivated plants (CJ Ward 15045; 15111; 15169). Clearly in southern Africa, as in other areas of distribution, C. corymbosus is synonymous with C. articulatus (representing an environmental or juvenile expression of the latter). We point to obvious difficulties that underlie the lack of corms on specimens of C. articulatus. These include the tropical watery habitat and the early decay of interconnecting stolons that leave the longer lasting culms isolated. Who has investigated adequately what exists in substrates where unfriendly biota (from bilharzia to crocodiles) lurk? Most herbarium specimens comprise a growing stolon severed at a point behind one or two flowering culms—young portions where corm enlargement has not yet commenced. Key to superscripts *articulatus (cormose) form; **corymbosa form Selected specimens – 1113 Angola (Cuanza Sul Prov.): Novo Redondo, Negunza River, CJ and JD Ward 76 (NU, UDW). – 1713 Namibia (Swartbooisdrif): Cunene River, Epupa Falls (-AA), CJ Ward 12047 (NU, UDW). – 1934 Mozambique (Beira): Gorongosa National Park, Pungwe River, CJ Ward 7797 (NU, UDW). – 2829 (Harrismith): Weenen County, Brakfontein, near Frere (-DD), Acocks 10827 (PRE). – 2831 (Nkandla): Mtunzini, Sihayi Lagoon (-DD), CJ and MC Ward 57 (NU, UDW); upper Mfule (-CB), CJ Ward 15044, 15045* (NH, NU, UDW, PRE). – 2832 (Mtubatuba): Hluhluwe Game Reserve, Hluhluwe River (-AA), CJ Ward 15111* (NH, NU, PRE, UDW); Richards Bay, Thulazihleka (-CC), CJ Ward 15169* (NH, NU, PRE, UDW). – 2930 (Pietermaritzburg): Merrivale Shooting Range, sedge marsh (-CA), Kotze 86, 147, 148** (NU); Isipingo Beach (-DD), CJ Ward 390, 664** (NU).
149
– 3030 (Port Shepstone): Mzimkhulu River mouth (-CB), Dre`ge 4406** (K, PRE), CJ Ward 14828** (NH, NU, PRE, UDW). – 3128 (Umtata): Elliotdale, The Haven (-BB), JL GordonGray 1007** (NU); Kei River Estuary (-CB), CJ Ward 14750 (GRA, NU, UDW).
Acknowledgements We express thanks for help received from the South African Biodiversity Institute, Pretoria, and the Herbarium, School of Botany and Zoology, University of KwaZulu-Natal, Pietermaritzburg. References Archer, C., 2003. Cyperaceae. In: Germishuizen, G., Meyer, N.L. (Eds.), Plants of Southern Africa: An Annotated Check List, Strelitzia, vol. 14. National Botanical Institute, Pretoria. Ayers, B. Bro, 1946. The genus Cyperus in Mexico. Catholic Universities of America, Biological Studies 1, 1 – 104. Boeckeler, O., 1869/70. Die Cyperaceae des Ko¨ninglichen Herbariums zu Berlin. Linnaea 36, 271 – 768. Clarke, C.B., 1894. Cyperaceae. In: Durand, T., Schinz, H.Conspectus Florae Africae ou E´nume´ration des Plantes d’Afrique, vol. 5. Friedlaender, Berlin and Klincksieck, Paris, pp. 526 – 692. Clarke, C.B., 1897/98. Cyperaceae. Flora Capensis, vol. 7. Reeve and Co, London, pp. 149 – 310. Clarke, C.B., 1901/02. Cyperaceae. Flora of Tropical Africa, vol. 8. Reeve and Co, London. Gordon-Gray, K.D., 1995. Cyperaceae in Natal: Strelitzia 2. National Botanical Institute, Pretoria. Haines, R.W., Lye, K.A., 1983. The Sedges and Rushes of East Africa. East African Natural History Society, Nairobi. Koyama, T.M., 1985. Cyperaceae. In: Dassanyaka, M.D., Fosberg, F.R. (Eds.), A revised Handbook to the Flora of Ceylon, vol. 5, pp. 125 – 405R Rotterdam. Ku¨kenthal, G. (1935/36) Cyperaceae. – Scirpoideae – Cypereae. Das Pflanzenreich 4, 20 heft 101: 163 – 671. Leipzig. Kunth, C.S., 1837. Cyperographica synoptica. Enumeration Plantarum 2. J Cotta, Stuttgart and Tu¨bingen. Metcalfe, C.R., 1971. Anatomy of the Monocotyledons: V. Cyperaceae. Clarendon Press, Oxford. Retief, E., Herman, P.P.J., 1997. Cyperaceae. Plants of the Northern Provinces of South Africa: Keys and Diagnostic Characters, Strelitzia, vol. 6. National Botanical Institute, Pretoria. Steudel, E.G. Von, 1855. Synopsis Plantarum Glumacearum, Pars 2 Cyperaceae. Stuttgart. Tucker, G.C., 1994. Revision of the Mexican Species of Cyperus (Cyperaceae). Systematic Botany Monographs, vol. 43. American Society of Plant Taxonomists, Ann Arbor, Michigan. Ward, C.J., 1980. The Plant Ecology of the Isipingo Beach Area, Natal, South Africa. Memoirs of the Botanical Survey of South Africa, vol. 45.
Studies in Cyperaceae in southern Africa 39: Cyperus articulatus L. and Cyperus corymbosus Rottb. K.D. Gordon-Gray a,*, C.J. Ward b, T.J. Edwards a a
School of Botany and Zoology, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa b P.O. Box 30501, Mayville 4058, South Africa Received 23 July 2004; accepted 14 June 2005
Abstract Cyperus articulatus L. and Cyperus corymbosus Rottb. were studied in southern Africa and were found to be synonymous. The latter bears laminae, has longer bracts and frequently has less septate culms than the former but these differences are phenotypic. Phenotypes formerly referred to C. corymbosus are generally rare and scattered, occupying the drier fringing zones of populations. A map of the distributional range of C. articulatus in southern Africa is provided, along with an illustration of the Fcorymbosus_ phenotype. D 2005 SAAB. Published by Elsevier B.V. All rights reserved. Keywords: Cyperus articulatus; Cyperus corymbosus; Southern Africa
Cyperus articulatus L. and Cyperus corymbosus Rottb., two tropical, perennial, rhizomatous, helophytic hydrophytes had been considered specifically distinct until Tucker (1994), after an extensive survey of Mexican, South American and Old World specimens, found he could not substantiate accepted character differences. Consequently he treated C. corymbosus as a synonym of C. articulatus. Study in southern Africa has supported Tucker’s treatment. We propose that the former is a laminate form with longer bracts and frequently less septatenoded culms. Commonly sympatric, the two entities are distributed widely; C. corymbosus is rare and scattered within or adjacent to more extensive stands of C. articulatus. Cyperus articulatus L. Sp. pl. 1: 44 (1753), Kunth: 53 (1837), Steudel: 30 (1855), Boeck.: 274 (1869/70), C.B.Clarke: 356 (1901/02), Ku¨ kenthal: 77 (1935), Ayers: 1 – 104 (1946), R.W.Haines and Lye: 183 (1983), Tucker: 95 (1994). Lectotype: Sloane, Voy. Jamaica Nat. His. 1: 121, t, 81, Figure 1 (1707). Cyperus corymbosus Rottb. Descr. pl. rar. 19 (1772); C.B.Clarke: 554 (1894), C.B.Clarke: 181 (1897/98), C.B.Clarke: 357 (1901/02), Ku¨kenthal.: 80 (1935), R.W.Haines and Lye: 183 (1983). Type: Suriname, Rolander s.n. (holo., Herb. Rottb. C.). * Corresponding author. E-mail address: [email protected] (K.D. Gordon-Gray).
C. articulatus often occurs in almost pure stands in tropical and warm temperate localities that provide permanent water. It is distinguished by its robust, leafless culms up to 1600 8 mm that are septate-noded and solid-pithed. In life the nodes are not always clearly defined externally but may be detected by gentle finger pressure or longitudinal sectioning. On drying, with shrinkage of pith, the septa stand out markedly. Bracts of the brown, branched, terminal inflorescences are short (5– 9 mm), stiff and sharp and never exceed primary ray length. The subterranean, curved stoloniferous rhizomes are scale-covered when young and terminate, at intervals, in erect, emergent culms. Corm development at the rhizome joints is not usually evident apart from occasional slight enlargements and we found no reference to corm production in the literature. In areas with seasonal climate, fluctuating water levels and greater competition, the plant facies is modified. Culms remain tall, but are slender with fewer septa. Occasionally short, inconspicuous leaf blades terminate the exposed lower leaf sheaths. Bracts are longer (20 –36 mm), becoming leaf-like, but seldom exceed the inflorescence (Fig. 1). C. corymbosus exhibits a close morphological relationship with this less robust expression of C. articulatus. Accepted differences between the two species have been based upon, for C. corymbosus, culms 1- or 2-bladed, bracts leaf-like, culm septa sparse or absent (Clarke, 1901/02; Ku¨kenthal, 1935;
0254-6299/$ - see front matter D 2005 SAAB. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.sajb.2005.06.004
148
K.D. Gordon-Gray et al. / South African Journal of Botany 72 (2006) 147 – 149
Fig. 1. Cyperus articulatus (corymbosus form): whole plant showing one leaf blade drying off. Culm articulations are not well defined (Ward 14828).
Ayers, 1946). Tucker (1994) was unable to substantiate these character differences in a study of Fsome 400 Old World and South American collections labeled as one or other of the species_. He therefore treated C. corymbosus and C. articulatus as synonymous. Metcalfe (1971) examined culms and rhizomes of C. articulatus from Tanzania and cited features of C. corymbosus
extracted from earlier literature without determining any significant anatomical divergence. However, this is a limited assessment requiring confirmation. Synonymy is further supported by distribution. C. articulatus, except for Malaysia, is common pantropically; C. corymbosus is reported from numerous localities within, or fringing the range of C. articulatus but is rare. The only exception to this pattern known to us is in Sri Lanka (Ceylon) where Koyama (1985) reported the apparent replacement of C. articulatus by C. corymbosus over a century. He commented after describing C. articulatus—FIt is rather interesting that this species has never been collected since Trimen’s time_ (c. 1888). Such a change could be the result of gradual modification of habitat, perhaps in conjunction with herbivory or other consistent mutilation. In southern Africa C. articulatus is well-known and widely represented in fresh, or slightly saline, mostly moving water of estuaries, river banks, lakes and wet grassland from sea level to about 1065m altitude (Fig. 2). It is reported from northern Namibia including Caprivi, Botswana, Swaziland and from the Limpopo, Mpumalanga and KwaZuluNatal (Archer, 2003; Retief and Herman, 1997) and the Eastern Cape provinces of South Africa. C. corymbosus is likewise widespread extra territorially, but poorly represented in herbaria and referred to as Frare_ or Funcommon_. Clarke (1897/98) in his treatment of Cyperus for southern Africa, omitted C. articulatus, but did include C. corymbosus, citing only Dre` ge 4406 from FNatal, near the mouth of the Umzimkulu River_ [now Mzimkhulu (Port Shepstone)] and adding FKunth, Enum. ii: 53, partly, i.e. the Dre`ge examples with septations of stems obsolete_: [Note: a fragment of the inflorescence of Dre`ge 4406 is preserved in PRE]. The species has been recollected from Dre`ge’s locality, nearly two centuries later (CJ Ward 14828). Ward (1980) recorded both species from Isipingo, noting the elongated rhizomes, tuberous [sic] only in C. corymbosus. The
Fig. 2. Known distribution of Cyperus articulatus in southern Africa.
K.D. Gordon-Gray et al. / South African Journal of Botany 72 (2006) 147 – 149
presence of well defined underground storage organs in this species (initially termed tubers, but now determined as corms, since they are stems which become hard and woody and are tunicated by frayed leaf sheaths) was a significant distinction from C. articulatus. The presence of corms in an allied species prompted the suggestion (Gordon-Gray, 1995) that C. corymbosus might be a hybrid in South Africa. Subsequent study has dispelled this hypothesis. Our experience is that corm production is induced in habitats influenced by seasonal change, fluctuating water levels and increased competition, and is almost always accompanied by sparse leaf blades and short leaf-like bracts. Such plants occur most commonly during colonization and in areas fringing favourable habitats. Further, we now have evidence of corms in what, on characters of emergent culms, must be named C. articulatus—from both wild collections and cultivated plants (CJ Ward 15045; 15111; 15169). Clearly in southern Africa, as in other areas of distribution, C. corymbosus is synonymous with C. articulatus (representing an environmental or juvenile expression of the latter). We point to obvious difficulties that underlie the lack of corms on specimens of C. articulatus. These include the tropical watery habitat and the early decay of interconnecting stolons that leave the longer lasting culms isolated. Who has investigated adequately what exists in substrates where unfriendly biota (from bilharzia to crocodiles) lurk? Most herbarium specimens comprise a growing stolon severed at a point behind one or two flowering culms—young portions where corm enlargement has not yet commenced. Key to superscripts *articulatus (cormose) form; **corymbosa form Selected specimens – 1113 Angola (Cuanza Sul Prov.): Novo Redondo, Negunza River, CJ and JD Ward 76 (NU, UDW). – 1713 Namibia (Swartbooisdrif): Cunene River, Epupa Falls (-AA), CJ Ward 12047 (NU, UDW). – 1934 Mozambique (Beira): Gorongosa National Park, Pungwe River, CJ Ward 7797 (NU, UDW). – 2829 (Harrismith): Weenen County, Brakfontein, near Frere (-DD), Acocks 10827 (PRE). – 2831 (Nkandla): Mtunzini, Sihayi Lagoon (-DD), CJ and MC Ward 57 (NU, UDW); upper Mfule (-CB), CJ Ward 15044, 15045* (NH, NU, UDW, PRE). – 2832 (Mtubatuba): Hluhluwe Game Reserve, Hluhluwe River (-AA), CJ Ward 15111* (NH, NU, PRE, UDW); Richards Bay, Thulazihleka (-CC), CJ Ward 15169* (NH, NU, PRE, UDW). – 2930 (Pietermaritzburg): Merrivale Shooting Range, sedge marsh (-CA), Kotze 86, 147, 148** (NU); Isipingo Beach (-DD), CJ Ward 390, 664** (NU).
149
– 3030 (Port Shepstone): Mzimkhulu River mouth (-CB), Dre`ge 4406** (K, PRE), CJ Ward 14828** (NH, NU, PRE, UDW). – 3128 (Umtata): Elliotdale, The Haven (-BB), JL GordonGray 1007** (NU); Kei River Estuary (-CB), CJ Ward 14750 (GRA, NU, UDW).
Acknowledgements We express thanks for help received from the South African Biodiversity Institute, Pretoria, and the Herbarium, School of Botany and Zoology, University of KwaZulu-Natal, Pietermaritzburg. References Archer, C., 2003. Cyperaceae. In: Germishuizen, G., Meyer, N.L. (Eds.), Plants of Southern Africa: An Annotated Check List, Strelitzia, vol. 14. National Botanical Institute, Pretoria. Ayers, B. Bro, 1946. The genus Cyperus in Mexico. Catholic Universities of America, Biological Studies 1, 1 – 104. Boeckeler, O., 1869/70. Die Cyperaceae des Ko¨ninglichen Herbariums zu Berlin. Linnaea 36, 271 – 768. Clarke, C.B., 1894. Cyperaceae. In: Durand, T., Schinz, H.Conspectus Florae Africae ou E´nume´ration des Plantes d’Afrique, vol. 5. Friedlaender, Berlin and Klincksieck, Paris, pp. 526 – 692. Clarke, C.B., 1897/98. Cyperaceae. Flora Capensis, vol. 7. Reeve and Co, London, pp. 149 – 310. Clarke, C.B., 1901/02. Cyperaceae. Flora of Tropical Africa, vol. 8. Reeve and Co, London. Gordon-Gray, K.D., 1995. Cyperaceae in Natal: Strelitzia 2. National Botanical Institute, Pretoria. Haines, R.W., Lye, K.A., 1983. The Sedges and Rushes of East Africa. East African Natural History Society, Nairobi. Koyama, T.M., 1985. Cyperaceae. In: Dassanyaka, M.D., Fosberg, F.R. (Eds.), A revised Handbook to the Flora of Ceylon, vol. 5, pp. 125 – 405R Rotterdam. Ku¨kenthal, G. (1935/36) Cyperaceae. – Scirpoideae – Cypereae. Das Pflanzenreich 4, 20 heft 101: 163 – 671. Leipzig. Kunth, C.S., 1837. Cyperographica synoptica. Enumeration Plantarum 2. J Cotta, Stuttgart and Tu¨bingen. Metcalfe, C.R., 1971. Anatomy of the Monocotyledons: V. Cyperaceae. Clarendon Press, Oxford. Retief, E., Herman, P.P.J., 1997. Cyperaceae. Plants of the Northern Provinces of South Africa: Keys and Diagnostic Characters, Strelitzia, vol. 6. National Botanical Institute, Pretoria. Steudel, E.G. Von, 1855. Synopsis Plantarum Glumacearum, Pars 2 Cyperaceae. Stuttgart. Tucker, G.C., 1994. Revision of the Mexican Species of Cyperus (Cyperaceae). Systematic Botany Monographs, vol. 43. American Society of Plant Taxonomists, Ann Arbor, Michigan. Ward, C.J., 1980. The Plant Ecology of the Isipingo Beach Area, Natal, South Africa. Memoirs of the Botanical Survey of South Africa, vol. 45.