Flora Of Southern Africa Research Articles

Alien woody plants are more versatile than native, but both share similar therapeutic redundancy in South Africa.

Understanding why alien plant species are incorporated into the medicinal flora in several local communities is central to invasion biology and ethnobiology. Theories suggest that alien plants are incorporated in local pharmacopoeias because they are more versatile or contribute unique secondary chemistry which make them less therapeutically redundant, or simply because they are locally more abundant than native species. However, a lack of a comprehensive test of these hypotheses limits our understanding of the dynamics of plants knowledge, use and potential implications for invasion. Here, we tested the predictions of several of these hypotheses using a unique dataset on the woody medicinal flora of southern Africa. We found that the size of a plant family predicts the number of medicinal plants in that family, a support for the non-random hypothesis of medicinal plant selection. However, we found no support for the diversification hypothesis: i) both alien and native plants were used in the treatment of similar diseases; ii) significantly more native species than alien contribute to disease treatments particularly of parasitic infections and obstetric-gynecological diseases, and iii) alien and native species share similar therapeutic redundancy. However, we found support for the versatility hypothesis, i.e., alien plants were more versatile than natives. These findings imply that, although alien plant species are not therapeutically unique, they do provide more uses than native plants (versatility), thus suggesting that they may not have been introduced primarily for therapeutic reasons. We call for similar studies to be carried out on alien herbaceous plants for a broader understanding of the integration of alien plants into the pharmacopoeias of the receiving communities.

New records of alien and potentially invasive grass (Poaceae) species for southern Africa

Background: The grasses (Poaceae) of the Flora of Southern Africa (FSA) region (i.e. Botswana, Eswatini, Lesotho, Namibia and South Africa) are relatively well documented, for both native and non-native species. Visiting taxonomic expertise nevertheless reveals new FSA and in-country records, particularly of non-native species. Such records provide an opportunity for improving biosecurity relating to potentially invasive but hitherto undetected non-native Poaceae in the FSA region.Objectives: To improve floristic data for non-native Poaceae occurring in theFSA region.Method: Field collections were made, herbarium collections, databases and relevant literature were studied.Results: New records are presented for non-native grasses that were encountered as locally common populations in the Drakensberg Mountain Centre of Floristic Endemism (DMC, Lesotho and South Africa). Festuca rubra and Agrostis capillaris are newly reported for sub-Saharan Africa and southern Africa and are also the first verified specimens reported for the African continent, with previous reports from northern-most Africa (Morocco, Algeria and/or Tunisia) uncertain. Jarava plumosa, introduced from South America and previously known for the whole of Africa from a single population in the Western Cape, South Africa, is newly reported from the border between the Eastern Cape, South Africa and Lesotho. The ecological implications, including the potential to become invasive, are discussed for each species, with taxonomic notes given to help differentiate them from closely resembling taxa.Conclusion: These new records of alien grass species raise concerns over their potential ecological impact, particularly as they are found in an area of conservation importance. Future efforts to monitor their distribution are of importance.

<p><strong>A taxonomic treatment of <em>Trisetopsis</em> (Poeae, Poaceae) in southern Africa</strong></p>

Trisetopsis, a genus of temperate C3 grasses, extends from the Arabian Peninsula southwards along the African mountains (temperate Afromontane Region) to sub-Saharan Africa and Madagascar, with a centre of diversity in southern Africa. A taxonomic treatment of Trisetopsis in the Flora of southern Africa (FSA) region is presented. The proposed classification is based on existing and comparative evidence derived from macromorphology, micromorphology, leaf anatomy, DNA sequences and geographical distribution. Fourteen species of Trisetopsis are recognized in the FSA region, all of them endemic to the region. Five of the species are rare; based on IUCN Red List categories and criteria, three species are considered “Vulnerable”, one as “Endangered, and one as “Critically Endangered” and probably “Extinct”. Improved and emended species descriptions, a key to the species, updated distribution maps and illustrations, especially of the spikelets, are provided. Lectotypes are designated for the names Avenastrum longum var. grande and Avena longa (basionym of Trisetopsis longa).

Spatial patterns, availability and cultural preferences for edible plants in southern Africa

AbstractAimWe investigated whether cross‐cultural food plant selection in southern Africa is best explained by language ancestry, floristic environment or subsistence strategy.LocationThe flora of southern Africa region.TaxaAll 1,740 edible plant taxa of southern Africa, representing 711 genera in 156 families.MethodsDistribution data of plants were overlapped in ArcMap with 19 language maps, eight biomes and all taxa with nutritional data. Six correlations were estimated between five pairwise distance matrices (language ancestry, geographical proximity, floristic and edible environments and utilized species) with Mantel tests using the ‘vegan’ package in R. Regression analyses were used to identify floristic and cultural preferences in food plant selection.ResultsSpatial autocorrelation did not influence the selection of edible plants by the 19 language groups of southern Africa (r = −.078). The floristic and edible environments had a strong correlation (r = .9743) while the distance matrices of the edible and actually utilized plants had a low correlation for 13 of the language groups (r = .2174). Regression analyses between the floristic and edible environments for the FSA region and three languages, representing hunter‐gatherers (Ju│’hoan), pastoralists (Khoekhoe) and agrarians (Venda) were all significant (p < .001) with high R2 values (respectively .6181, .7702, .6654 and .7900), as were the relationship (p < .001) between what is edible and what was actually utilized. Surprisingly, the Apocynaceae had a much higher residual value than globally important food plant families. Vitamin C of fruits seems to have higher levels along the coastal regions, and carbohydrates in underground storage organs have higher levels in the summer‐arid western region.Main conclusionsThere is an apparent preference for certain food plant families in southern Africa. This selection appears to be driven by subsistence strategy, based on the categories of plants preferred by the three representative language groups.

Chamaecrista falcata (Caesalpinioideae, Cassieae, Cassiinae), a new species from South Africa

Chamaecrista falcata Musandiwa & Boatwr., a new species from the northern coastal regions of KwaZulu-Natal and the Waterberg in Limpopo, is described bringing the number of recognised species of Chamaecrista in southern Africa to 13. This taxon was previously confused with Chamaecrista capensis and treated under this species in the Flora of Southern Africa. The new species shares stipitate extrafloral nectaries with Chamaecrista grantii but is distinguished by its falcate leaflets with a strongly excentric midrib. A detailed description of the new species is presented, together with a distribution map and illustrations of its diagnostic characters.

An inventory and analysis of the food plants of southern Africa

The food plants of southern Africa have not yet been been systematically recorded and the main patterns of plant use have therefore never been studied. The book by Fox and Norwood Young (1982) entitled “Food from the Veld” has been the most comprehensive to date and has become the standard reference work on the subject. However, this publication has become outdated and it is evident that many species were not included. We present here, for the first time, a comprehensive inventory and checklist of the edible plants of southern Africa, i.e., the Flora of Southern Africa (FSA) region. Seventy-four literature sources, including books, journal articles, checklists, grey literature and published ethnobotanical surveys were used to compile the inventory, which includes 1740 species (more than double the number listed by Fox and Norwood Young). All edible plants were marked-off in an Excel spreadsheet of all southern African plant species, made available by the South African National Biodiversity Institute (SANBI). Using the Excel format, it was possible to easily explore the main patterns relating to the frequency of citation of the species, the number of species at different taxonomic ranks (families, genera and species), the plant parts that are used and the use categories within the region. For a selection of 13 indigenous cultural/language groups (for which adequate information was available), we quantified the local preferences (for the most species-rich families, the most commonly used plant parts and the most frequent categories of use. The food plant data for southern Africa were also compared to sub-Saharan Africa and the entire world. Surprisingly, it was found that the Apocynaceae was the most species-rich family of southern Africa food plants, with a total of 137 species, followed by the Fabaceae (135 species), Asteraceae (94 species) and Poaceae (73 species). A similar pattern was found in sub-Saharan Africa, but with Fabaceae in the first position, followed by Apocynaceae. The family-level pattern for the entire world is different, where the Apocynaceae is unimportant, being replaced by Rosaceae (the last-mentioned is of very low significance in Africa). The most species-rich food plant genus in southern Africa is Searsia, while Solanum nigrum and Sclerocarya birrea have the highest frequency of citation in the literature. The most popular plant part used as a food in southern Africa, as well as in the entire world, are fruits, followed by leaves and then underground storage organs. The most species-rich category of food plant use is those consumed raw (and mostly in situ) as snacks, followed by those which are cooked as vegetables. The Apocynaceae have mostly edible underground storage organs as the edible parts, while Fabaceae is more diverse. Fruits and leaves have been determined as the most important plant parts used as food for most of the cultural groups except for the Khoekhoe group, where underground parts are the most important. For all of the cultural groups, plants used for snacks were the most important. A chronological list of publications shows that there were seven major contributions since the first survey by Van der Stel in 1685. The comprehensive inventory provides profound new insights into foraging and human food ecology and may also have value in interpreting and reconstructing the availability of food plants during the evolution of early humans in southern Africa.

The Evolution of Regional Species Richness: The History of the Southern African Flora

The flora of southern Africa is, for its latitude and area, very species-rich. Although the hyperdiverse Cape flora contributes almost half of this richness, three other radiations (desert, grassland, and woodland) contribute significantly to the botanical wealth of southern Africa. Each radiation occurs in a different ecological setting and has a different diversification history. Such parallel radiations can develop in suitably complex environments, given gradual change through time and no region-wide catastrophes. These four radiations cross-seeded each other, with clades spawning subclades in other radiations, thus linking all four into one complex radiation. This led to an increase in the number of diversifying clades in each radiation. Such complex radiations accumulate diversifying lineages over a long time, spawn daughter radiations on other continents, and become powerhouses of global-biodiversity generation. We suggest that several of the most species-rich regions may harbor such complex radiations.

Recircumscription and distribution of elements of the <i>‘Ceterach cordatum’</i> complex (<i>Asplenium</i>: Aspleniaceae) in southern Africa

Ceterachoid aspleniums in southern Africa have long been treated as a single widespread and variable taxon, Asplenium cordatum (Thunb.) Sw. (= Ceterach cordatum Thunb.). In addition to A. cordatum, a further two ceterachoid taxa are now recognized as occurring in the Flora of southern Africa (FSA) region, namely A. capense (Kunze) Bir, Fraser-Jenk. Lovis and A. phillipsianum (Kümmerle) Bir, Fraser-Jenk. Lovis. We provide full descriptions and distributions of these three taxa.

A conspectus of <i>Combretum</i> (Combretaceae) in southern Africa, with taxonomic and nomenclatural notes on species and sections

Two subgenera of Combretum Loefl. occur in the Flora of southern Africa (FSA) region. Previous sectional classifications were assessed in view of molecular evidence and accordingly modified. Ten sections in subgen. Combretum, 25 species and eight subspecies are recognized. Subgen. Cacoucia (Aubl.) Exell Stace comprises four sections and seven species. C. engleri Schinz, C. paniculatum Vent. and C. tenuipes Engl. Diels are reinstated as distinct species separate from C. schumannii Engl., C. microphyllum Klotzsch and C. padoides Engl. Diels, respectively. C. schumannii occurs outside the FSA region. Records of C. adenogonium Steud. ex A.Rich., C. platypetalum Welw. ex M.A.Lawson subsp. oatesii (Rolfe) Exell and subsp. baumii (Engl. Gilg) Exell in Botswana are doubtful. C. celastroides Welw. ex M.A.Lawson subsp. orientale Exell is elevated to species level as C. patelliforme Engl. Diels. C. grandifolium F.Hoffm. is reduced to C. psidioides Welw. subsp. grandifolium (F.Hoffm.) Jordaan. Twenty-six names are lectotypified. The type, a full synonymy, other nomenclatural and taxonomic information, the full distribution range and a distribution map are provided for each taxon. Selected specimens examined are given for poorly known species. Keys to subgenera, sections and species are provided.

Succulent flora of Southern Africa

Succulent flora of Southern Africa

Patterns of plant species richness of temperate and tropical grassland in South Africa

Grasslands are so called based on the structural facet of this vegetation type. Grasslands are dominated by species of the Poaceae, are mostly one-layered in structure with few trees and shrubs, and are climatically controlled (Mucina & Rutherford 2006). Grasslands occur in both temperate and tropical regions of the world. In southern Africa, Mucina & Rutherford (2006) consider grasslands to be either sub-tropical or temperate. The differentiation between these two grassland types is based on the factors responsible for the maintenance thereof. Tropical grasslands are often regarded as secondary (e.g. fire maintained) or edaphic (e.g. shallow water table) (Matthews et al. 1999). Temperate grasslands are thought to be naturally maintained by subzero temperatures and dry winters, in combination with fire, which prevent colonisation of grasslands by the tropically-derived tree flora of southern Africa (Bredenkamp et al. 2002). South African grasslands are characterised by plant species with special modified underground organs which enable them to escape fire (e.g. geoxylic suffrutices; White 1977) or become dormant in winter (e.g. geophytes; Tainton & Mentis 1984) when growing conditions become unfavourable. Such adaptations are thought to be major mechanisms whereby grassland plants survive severely cold, dry winters and subsequent fires in temperate southern African grasslands (Bredenkamp et al. 2002). Grassland species, especially perennial forbs, are usually quick in responding to the effects of fire and such plants are characterised by profuse flowering and mass seed production (Retief & Van Wyk 2002).

Gradual speciation in a global hotspot of plant diversity

The speciation process that underlies recent, rapid radiations of plants is controversial, and suggested mechanisms range from pollinator or ecological niche differentiation to allopatry and nonadaptive divergence. Phylogenetic approaches to locating the most appropriate speciation models have been constrained by the low levels of molecular divergence between recently diverged species, which are typical of recent, rapid radiations. In this issue of Molecular Ecology, Rymer et al. (2010) used coalescence analyses of sequence data and genome scans of Amplified Fragment Length Polymorphism (AFLP) loci to demonstrate that in a species complex in the irid genus Gladiolus, a member of the hyper diverse Cape flora of southern Africa, speciation is a gradual process. Older divergences are genetically more differentiated, and show a greater difference in flowering time and floral morphology, than taxa that diverged more recently. There is no evidence of any abrupt events. Gene flow is limited by shifts in flowering time and floral morphology; thus, by pre-zygotic rather than by post-zygotic mechanisms, these evolved together with the occupation of somewhat different habitats. This research gives the first critical insight into how the remarkable diversity in a diversity hotspot could have arisen. More importantly, it demonstrates that the speciation process in recent, rapid radiations is tractable and can be investigated with suitable genetic tools.

The pollination niche and its role in the diversification and maintenance of the southern African flora

The flora of southern Africa has exceptional species richness and endemism, making it an ideal system for studying the patterns and processes of evolutionary diversification. Using a wealth of recent case studies, I examine the evidence for pollinator-driven diversification in this flora. Pollination systems, which represent available niches for ecological diversification, are characterized in southern Africa by a high level of ecological and evolutionary specialization on the part of plants, and, in some cases, by pollinators as well. These systems are asymmetric, with entire plant guilds commonly specialized for a particular pollinator species or functional type, resulting in obvious convergent floral evolution among guild members. Identified modes of plant lineage diversification involving adaptation to pollinators in these guilds include (i) shifts between pollination systems, (ii) divergent use of the same pollinator, (iii) coevolution, (iv) trait tracking, and (v) floral mimicry of different model species. Microevolutionary studies confirm that pollinator shifts can be precipitated when a plant species encounters a novel pollinator fauna on its range margin, and macroevolutionary studies confirm frequent pollinator shifts associated with lineage diversification. As Darwin first noted, evolutionary specialization for particular pollinators, when resulting in ecological dependency, may increase the risk of plant extinction. I thus also consider the evidence that disturbance provokes pollination failure in some southern African plants with specialized pollination systems.

An overview of plant–pollinator relationships in southern Africa

A particularly rich array of pollination systems is represented in the flora of southern Africa. Hopliine beetles, long-proboscid flies, satyrine butterflies, hawk moths, birds and rodents appear to assume greater importance as pollinators than they do in other temperate regions. These ’alternative’ pollination systems may have developed because the bee-fauna of southern Africa is not particularly rich relative to the flora. Pollination by moths, for example, is relatively frequent in the eastern half of southern Africa where bee diversity is lowest. Pollination systems in southern Africa are relatively specialized and shifts between pollinators have been shown to be an important driving force in plant diversification and speciation. Changes in land-use, particularly afforestation and ploughing of grasslands, invasion of alien plants, overgrazing and urban developments have disrupted these mutualisms with mostly unknown consequences for ecosystem functioning. Future research will be directed at expanding our knowledge of pollination systems, with a strong focus on the conservation of mutualistic ecological interactions.

The genus <i>Buglossoides</i> (Boraginaceae) in southern Africa

The genus Buglossoides Moench, a member of the family Boraginaceae. subfamily Boraginoideae. tribe Lithospermeae. is revised tor the Flora of southern Africa (FSA) region. Buglossoides comprises about seven species of annual, biennial or perennial herbs and subshrubs native to Asia, southern Europe and northern Africa. B. arvensis (L.) I.M Johnst.. a naturalized weed in many parts of the world, is the only member of the genus represented in the flora of southern Africa, presumably introduced with imported cereal seed. Although the similar polyaperturate pollen grains of Buglossoides and Lithospermum support the view that they are congeneric, they are retained as separate entities here. Diagnostic characters, a full description, various illustrations and a distribution map of B. arvensis in southern Africa are given.

Flora of Southern Africa, Which Deals with the Territories of South Africa, Lesotho, Swaziland, Namibia and Botswana

Flora of Southern Africa, Which Deals with the Territories of South Africa, Lesotho, Swaziland, Namibia and Botswana

Brachystelma swarupa (Apocynaceae): A New Species from India

The Afro-Asiatic genus Brachystelma Sims (Apocynaceae Ceropegieae;, see Bruyns & Forster 1991; Swarupanandan et al. 1996; Endress & Bruyns 2000) contains approximately 130 species (rather than the 100 or so species generally quoted (Dyer 1980, 1983)), with perhaps as many as seventeen in India. The genus has never been revised over its entire geographic range, but two checklists (Walker 1982; Boele et al. 1987) list 110 and 111 species respectively and a further 20 species have been described since. The most comprehensive regional treatment is for the Flora of Southern Africa (Dyer 1980, 1983), the region with the highest concentration of species (69). Smaller regional accounts or checklists have been compiled for other countries Botswana, Malawi and Lesotho (Hargreaves 1999); Zimbabwe (PercyLancaster 1988; Boele 1989); East Africa (Newton 1996); West tropical Africa (Meve & Porembski 1993); Australia, New Guinea and Indonesia (Forster 1988, 1990) but India still awaits a synthetic account. Generic delimitation has been, and remains, controversial. Dyer (1980, 1983) included 10 genera in synonymy under Brachystelma including the superficially distinctive Dichaelia with its lantern-like flowers. Peckover (1996) proposed the inclusion of Tenaris and Macropetalum, arguing that the characters used to define these genera are inconsistent, but this has been disputed by Victor & Nicholas (1998). But the problem goes wider still in the absence of reliable coronal characters, keys to distinguish Brachystelma from Ceropegia and Riocreuxia resort to the length of the corolla tube, and there is occasional reassortment of atypical species most recently B. nepalense was transferred into Brachystelma from Riocreuxia (Meve 1997). Gilbert (in press), commenting on the problem for taxa treated in the forthcoming Flora of Ethiopia and Eritrea, states: 'The distinction [of Brachystelma] from Ceropegia is difficult as there are no characters that give a clear division.

Court, D. 2000. Succulent flora of Southern Africa. Revised edition.

Court, D. 2000. Succulent flora of Southern Africa. Revised edition.

Red Data List of southern African plants. 1. corrections and additions

No abstract available

The influence of rainfall on vegetation composition in different conditional states

The impact of ecological factors such as changes in rainfall could lead to large compositional changes in the diverse indigenous flora of southern Africa. A study was therefore initiated to determine the influence of rainfall conditions on species composition changes, which could serve as a basis for determining the long term influence of rainfall increase (e.g. cloud stimulation) and rainfall decrease (e.g. long term droughts). Certain species were found to occur in all the rainfall zones while others were limited to either the high or the low rainfall area. The reaction of species on the rainfall gradient also differs in vegetation representing different degradation stadia. The predictions of the reactions of key species on rainfall decrease or increase are of special importance for the eventual determination of grazing capacity.