K.D. Gordon-Gray

Achene structure and taxonomy of North American Bolboschoenus (Cyperaceae)

Surface and transverse section achene structures ofBolboschoenus maritimus, B. robustus, B. fluviatilis, B. novae-angliae, B. glaucus, and the putative hybridsB. maritimus × B. rubustus andB. glaucus × B. maritimus from North America are described and illustrated with SEM micrographs. The same three type of pericarp structure reported by Browning and Gordon-Gray (1993) from southern Africa were found except that the “type 2” (B. glaucus) was not matched precisely. Intermediate achene structures and other evidence support both the hybrid origin ofB. novae-angliae (=B. fluviatilis × B. robustus) and hybridization betweenB. glaucus andB. maritimus. The new combinationBolboschoenus novae-angliae is made.

Patterns of fruit morphology in Bolboschoenus (Cyperaceae) and their global distribution

Assessment of pericarp surface patterning and anatomy in Bolboschoenus has shown correlation with other features such as nut conformation and style branch number. On the fruit morphology in particular, the genus is seen to comprise three structural patterns, herein conveniently termed ‘Elements’: one with two-angled fruits bearing two-branched styles (Element 1); another with three-angled fruits bearing three-branched styles (Element 2). The third pattern (Element 3), which is possibly of hybrid origin, appears derived. Pericarp patterns are illustrated by electron-scanning. A list of species found to be representative of each Element is provided, as is a map (in colour) showing their general distribution.

Studies in Cyperaceae in southern Africa 26: Glume epidermal silica deposits as a character in generic delimitation of Costularia and Cyathocoma as distinct from Tetraria and other allies

Differences of opinion encountered in the generic placement of species that fall within Costularia C.B. Clarke, Cyathocoma Nees (= Macrochaetium Steud.) and Tetraria P. Beauv., are outlined and attention is drawn to the inadequate documentation of Cape species and genera of the tribe Schoeneae Dum., particularly in relation to possible extra territorial relatives. Using results obtained from electron scanning of surface topography of the epidermal cells of the flanks of mature glumes, a case is made for the resuscitation of an already well-known technique, namely, the microphotography of nail varnish imprints, as a cheap and rapid means of contributing to the reliable generic identification collectively, of Costularia and Cyathocoma, as distinct from Tetraria, Epischoenus and Carpha.

Studies in Cyperaceae in southern Africa. 21: The taxonomic significance of the achene and its embryo in Bolboschoenus

Morphological variability encountered within Bolboschoenus maritimus (L.) Palla in the area of the Flora of southern Africa (FSA) led to the study of the achenes, particularly details of the pericarp, and embryos of this species and of B. nobilis. For confirmation of findings, some extraterritorial specimens were also investigated. Differences in exocarp structure and in embryo size and shape were revealed. These may prove useful in the hierarchical classification of Bolboschoenus once world representatives have been studied. It is considered premature to modify the existing classification applied to FSA plants, except to confirm the presence of two entities within B. maritimus sensu Browning & Gordon-Gray 1992.

Studies in Cyperaceae in southern Africa. 19: The genus Bolboschoenus

The genus Bolboschoenus (Ascherson) Palla, a segregate from Scirpus L. sensu lato , is considered for the geographical area of the Flora of southern Africa. Two species are recognized. B. maritimus (L.) Palla is widespread and variable; B. nobilis (Ridley) Goetghebeur & D.A. Simpson is restricted to Namibia. Descriptions, known distributional areas and ecological notes are given for both species, as is a key for identification. Electron micrographs of achenes and achene surfaces are provided.

Studies in Cyperaceae in southern Africa. 30: aspects of the relationship between Cyathocoma and Costularia

The relationship between Costularia natalensis C.B. Clarke and the two endemic species Cyathocoma ecklonii Nees and C. hexandra (Nees) J. Browning comb. nov., previously foreshadowed by a study of epidermal silica deposits, is substantiated by further evidence of morphological similarity. Floret number and disposition in the spikelet is considered for these taxa, and fruit structure, including pericarp anatomy, is described and illustrated. Costularia brevicautis C.B. Clarke is contrasted with the other three. In several of its characteristics it resembles the southern genus Oreobolus R. Br., particularly O. ambiguus Kuk. & Stern, however, differences from both Costularia and Oreobolus are sufficient for it to be raised to independent generic ranking.

Studies in Cyperaceae in southern Africa. 29: Costularia natalensis, an endangered species

Costularia natalensis is a poorly known subSaharan African endemic that should be regarded as endangered. Populations are restricted to highland massifs from Malawi southwards to South Africa (KwaZulu-Natal); small in extent, and widely scattered, they show no obvious evidence of regeneration. Generic relationships of the species are uncertain. A comprehensive description is given, supplemented by notes on morphological variability, fruit dispersal and ecological preferences, and distribution.

Studies in Cyperaceae in southern Africa 27: a contribution to knowledge of spikelet morphology in Epischoenus and the relationship of this genus to Schoenus

Spikelet morphology in the endemic, southern African genus Epischoenus C.B. Clarke is considered and new information is given. Some problems of interpretation are discussed. The relationship of Epischoenus to the older and larger genus Schoenus L., which is predominantly SE Asian and Australian, is further emphasized by the new information provided. The question arises as to whether Epischoenus is separable from Schoenus by definite morphological discontinuity, or whether it is primarily on continental location that generic limitation rests. Species delimitation in Epischoenus is unsatisfactory and in need of revision. Field study of living organisms from stage to stage of development is required, but made difficult by habitats.

Siphonochilus aethiopicus (Zingiberaceae): observations on floral and reproductive biology

A taxonomic revision for the Flora of Southern Africa of Siphonochilus (Zingiberaceae) awaits publication (R.M. Smith, RBG, Edin., pers. comm. to ABC, 1987). In this revision the two southern African species, S. aethiopicus (Schweinf.) B.L. Burtt and S. natalensis (Schltr. & Schum.) Wood & Franks will be united. For the purposes of this article this conspecificity is assumed. S. aethiopicus has a distribution in Africa southwards from Senegal and Ethiopia to the Transvaal. Futher south wild populations are not now known, the species having disappeared from the natural flora of Natal. Rhizomes are extensively used in traditional African medicine and cultural practices. Floral and reproductive biology is poorly documented, but important if cultivated stocks in southern Africa are to be maintained. Monitoring of plants under cultivation and semi-natural conditions did not support the record of polygamy within the species. One type of flower only was produced by an individual rhizome. Bisexual flowers may mature to fruits containing viable seed that will germinate in situ. Ovaries of female flowers did not develop, suggesting apomixis does not operate in seed production. The internal surfaces of the staminodial tubes of bisexual flowers bore scattered glandular trichomes; those of female flowers densely placed multicellular papillae. Bisexual and female flowers are thus strikingly different in detailed structure as well as in general morphological form.

Studies in Cyperaceae in southern Africa 35: a field study of Bolboschoenus maritimus s.l. in a western Cape wetland

An account is given of reproductive features, especially the inflorescence, spikelets and achenes, including pericarp anatomy and embryos, of a population of Bolboschoenus maritimus (L.) Palla sensu lato at Verlorenvlei, an estuarine lake on the west coast of Cape Province (now Northern Cape), South Africa. The variation encountered is recorded by means of illustrations and tables, and speculative explanation of the range of morphological form reported is offered to promote further study. Some comparisons of achenes, pericarp anatomy and embryos from populations in the general area of the Northern and Eastern Cape are made with those from Verlorenvlei.