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Publications (55)
Key, checklist and species descriptions of the Apocynaceae taxa from the Eastern Cape Province in South Africa.
Two new combinations are made for taxa that were previously attributed to the genus Schizoglossum and are now placed in the genus Stenostelma. Included is the typification of Stenostelma capense, S. carinatum, S. corniculatum, S. eustegioides and S. periglossoides. Two new species, Stenostelma ligulatum and S. urceolatum, both with restricted distr...
Owing to the brief description, and in the absence of any known type collection of Cordylogyne argillicola, the application of the name remained unresolved for over a century. Type material that was recently discovered in the South African Museum (SAM) collection has made it possible to give an amplified description here. A depiction from the type...
The Schizoglossum complex and its allies are placed within Asclepiadoideae, which is one of five subfamilies in Apocynaceae. Of the main centres of diversity for this subfamily the eastern and southern Africa centre is the most diverse (± 86 genera). In southern Africa subtribe Asclepiadinae is the most diverse (representing ± 64% of the taxa) and...
Aspidoglossum albocoronatum Bester & Nicholas is a unique species from Sekhukhuneland in Mpumalanga and southern Leolo Mountains in Limpopo, South Africa. In morphological character it belongs to the southern African Schizoglossum complex (which includes the genera Aspidoglossum, Schizoglossum s.s. and Miraglossum). A description, line drawings and...
Periglossum podoptyches is described as a new species from the KwaZulu-Natal Province of South Africa. As a rare species its conservation status is assessed as Vulnerable. This new species is closely related to both Periglossum mackenii and P. kassnerianum from which it differs mainly in having folded flaps of tissue at the base of the face of the...
Recently developed computational tools in ITS2 sequence-structure phylogenetics are improving tree robustness by exploitation of the added information content of the secondary structure. Despite this strength, however, their adoption for species-level clarifications in angiosperms has been slow. We investigate the utility of combining ITS2 sequence...
A new species from southern Africa namely Schizoglossum austromontanum is described. Line-drawings, scans of the type material, images and a conservation assessment are provided.
Strychnos is the largest genus of the Loganiaceae with about 200 species distributed across Africa (including Madagascar), the Americas, Australia and Asia. Recent molecular phylogenetic effort at elucidating relationships globally provided a useful overview for the genus, based on the internal transcribed spacer (ITS) data. However, an understandi...
Haloxylon salicornicum is a perennial shrub that grows in sandy and stony desert areas. This species produces two types of dispersal unit with yellow and pink winged perianths that are wind dispersed. This species has been considered as an excellent sand binder and can tolerate extreme temperature, drought and salinity. We compared the germination...
Aspidoglossum is endemic to Africa and widely distributed throughout southern and tropical Africa. Its members are mainly found along the eastern side of the subcontinent with a diversification in southern Africa. It was first described by Ernest Meyer in 1838 comprising three species; Aspidoglossum biflorum, A. heterophyllum and A. fasciculare. Th...
Schizoglossum theileri (Apocynaceae, Asclepiadoideae) is found to be conspecific with Asclepias meliodora and is here formally reduced to synonymy under the latter.
There is currently a major gap in our understanding of early-greening in savanna trees, particularly in southern Africa. We monitored the phenology of a stand of Burkea africana and the surrounding grasses in the Nylsvley Nature Reserve, South Africa at weekly intervals over the green-up periods (August–November) between 2012 and 2014. We compared...
Asclepias xysmalobioides Hilliard & B.L. Burtt (1986: 193) is a later homonym of Asclepias xysmalobioides S. Moore (1912: 342). There are no valid synonyms available, and so we propose the new name Asclepias montevaga M. Glen, Nicholas & Bester here.
In this study, the chemical composition and antimicrobial activity of the essential oils from the leaves of Ocimum obovatum were investigated. Hydrodistillation yielded 43 compounds representing 99.5% of the oil. The composition of the oil was analyzed using gas chromatography and mass spectrometry (GC-MS). The main compounds detected were phytol (...
The Asclepiadoideae are one of five subfamilies within Apocynaceae and consist of approximately 3 000 species in ± 180 genera. This subfamily has three main centres of diversity, of which the eastern and southern Africa centre is the most diverse (represented by ± 86 genera). In southern Africa the tribe Asclepiadeae is represented by ± 26 genera (...
The micromorphology of the leaf epidermis of 11 species across four sections of southern African Strychnos was investigated using light microscopy and scanning electron microscopy. In addition to this, preliminary genome size was assessed with flow cytometry. Qualitative and quantitative results are presented for stomata, trichome and cuticular wax...
This study characterises the micromorphology, ultrastructure and main chemical constituents of the foliar glandular trichomes of Ocimum obovatum using light and electron microscopy and a variety of histochemical tests. Two types of glandular trichomes occur on the leaves: large peltate and small capitate. The head of each peltate trichome is made u...
The last full revision of Schizoglossum sensu lato was done by N.E. Brown in the Flora of tropical Africa (1902-1903) and Flora Capensis (1909) respectively. A.A. Bullock did some work in the genus on the tropical African taxa in 1952-1963. In 1984 F. Kupicha partly revised the genus and split it into Schizoglossum s.s., Miraglossum and Aspidogloss...
Leaves can be a useful source of taxonomic information in plants particularly when flowers and fruits are absent during certain periods of the year. In this study, we applied an elliptic Fourier analysis (EFA)‐based morphometric technique to assess leaf morphological divergence among four species of southern African Strychnos section Densiflorae. U...
Pachycarpus acidostelma M. Glen & Nicholas (Apocynaceae, Asclepiadoideae) is a new species described from the KwaZulu-Natal Province of South Africa. The new taxon is differentiated from other closely related Pachycarpus E. Mey. species (P. scaber (Harv.) N. E. Br. and P. asperifolius Meisn.) by its small stature, the catilliform or saucer-shaped c...
The genus Aspidoglossum, an endemic to Africa, is widely distributed throughout southern and tropical Africa. Found mainly along the eastern side of the subcontinent, it has its highest diversity in southern Africa. The genus was first described by E. Meyer in 1838 and at the time consisted of only three species: A. biflorum, A. heterophyllum and A...
Extracts of in vitro leaves, field leaves and seeds of the leguminous plant Lessertia frutescens were analyzed using spectrophotometric and gravimetric methods, to the effect of quantitative comparison of their phenolic, flavonoid, alkaloid and saponin contents. As compared to the field leaves and seeds, saponins were found to be most abundantly re...
Lessertia frutescens L., commonly known as cancer-bush, is a medicinally reputed plant species indigenous to southern Africa. Field leaf extracts
of this species are known to exhibit many curative properties. However, little is known about the bioactive compounds that
are present in in vitro leaf extracts and seed extracts. The objective of this st...
This paper reports the results of a study on the morphology, mode of secretion, ultrastructure and histochemistry of leaf secretory scales of Combretum molle using both light and electron microscopy. The density of the secretory scales is higher on the abaxial leaf surface in the intervein areas. Each secretory scale is made up of a basal epidermal...
Using a combination of light (stereo and compound) and scaning electron microscopy, this study investigates the distribution and morphology of foliar trichomes of Orthosiphon labiatus (Lamiaceae) at different stages of leaf development. Three types of trichomes were observed: two glandular types (large peltate and small capitate) and one non-glandu...
A simple protocol for direct shoot organogenesis and plant regeneration in Lessertia frutescens using hypocotyl and cotyledon segments is reported. l-canavanine content in the derived shoots is also quantified. Media containing different concentrations and combinations of
the cytokinins kinetin (K) and benzyladenine (BA) were tested for shoot induc...
Plectranthus laxiflorus (family Lamiaceae), is an important medicinal plant, distributed east of the southern continental escarpment from Humansdorp in the Eastern Cape province of South Africa. The distribution and morphology of leaf trichomes of P. laxiflorus were investigated using a combination of light and scanning electron microscopy. The lea...
This study describes a protocol for rapid and efficient in vitro propagation of Lessertia frutescens (cancer bush), a medicinally important plant species native to southern Africa. Single node explants were grown in various culture regimes of MS medium containing 30 g/l sucrose supplemented with various concentrations of cytokinins and auxins and s...
The present study reports a simple protocol for indirect shoot organogenesis and plant regeneration of Sutherlandia using rachis and stem segments. Different concentrations (0.0–68.08μmoll−1) of thidiazuron (TDZ) were used for callus induction and shoot organogenesis. The highest percentage of callus formation
(97.5%) and the highest percentage of...
The micromorphology of foliar trichomes of Hypoestes aristata var. aristata was studied using stereo, light and scanning microscopy (SEM). This genus belongs to the advanced angiosperm family Acanthaceae, for which few micromorphological leaf studies exist. Results revealed both glandular and non-glandular trichomes, the latter being more abundant...
The morphology and distribution of leaf trichomes of Tetradenia riparia were studied using light and scanning microscopy. Three morphologically distinct types of trichomes were observed on T. riparia leaf surfaces: glandular capitate (short and long stalked), peltate and non-glandular. The glandular and non-glandular trichomes were present in abund...
of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009
This paper compares the changes in water content, chlorophyll a fluorescence and leaf ultrastructure during dehydration and rehydration in two desiccation tolerant plants Xerophyta viscosa and X. retinervis. Both species showed decreasing quantum efficiency of photosystem 2 (Fv/Fm) with decreasing water content. Extreme water loss observed after 25...
Pachycarpus acidostelma M. Glen & Nicholas (Apocynaceae, Asclepiadoideae) is a new species described from the KwaZulu-Natal Province of South Africa. The new taxon is differentiated from other closely related Pachycarpus E. Mey. species (P. scaber (Harv.) N. E. Br. and P. asperifolius Meisn.) by its small stature, the catilliform or saucer-shaped c...
Cancer bush (Sutherlandia frutescens L.) is a medicinally important perennial legume native to southern Africa. S. frutescens seeds exhibit dormancy like many other legumes. Experiments using physical, mechanical and chemical pre-sowing treatments were conducted to determine
the germination response of this species. Among various treatments, soakin...
TRANSFER OF SCHIZOGLOSSUM UMBELLULIFERUMIO STENOSTELMA, AND ITS NEOTYPIFICATION (ASCLEPIADOIDEAE)
A first approximation of evolutionary relationships within the Asclepiadinae (Apocynaceae: Asclepiadoideae) is inferred from two DNA data sets, from the nuclear ITS region, and from plastid trnT-L and trnL-F spacers and trnL intron. Both the subtribe as a whole and the phylogenetic radiation of largely herbaceous genera around Asclepias are monophy...
Gomphocarpus is a genus of mostly shrubby herbs with non-tuberous rootstocks native to
Africa, Arabia and adjacent territories south of the Dead Sea. The genus is here restricted to a
putatively monophyletic assemblage of 20 species in several complexes. The corona lobe is
remarkably constant in form within a species and is the most useful organ fo...
The Gentianales as circumscribed by Benson, Cronquist, Dahlgren, Goldberg, Hey wood et al., Melchior, Stebbins, Takhtajan, and Thorne is investigated. From these a consensus classification (not in the cladistic sense) or classificatory model for the order is proposed. This classification is discussed, as are the relationships of the taxa within it....
Thesis (M.Sc.)--University of Natal, Pietermaritzburg, 1982. Bibliography: leaves 475-500.