Ronell R. Klopper

Evolutionary history and leaf succulence as explanations for medicinal use in aloes and the global popularity of Aloe vera

BackgroundAloe vera supports a substantial global trade yet its wild origins, and explanations for its popularity over 500 related Aloe species in one of the world’s largest succulent groups, have remained uncertain. We developed an explicit phylogenetic framework to explore links between the rich traditions of medicinal use and leaf succulence in aloes.ResultsThe phylogenetic hypothesis clarifies the origins of Aloe vera to the Arabian Peninsula at the northernmost limits of the range for aloes. The genus Aloe originated in southern Africa ~16 million years ago and underwent two major radiations driven by different speciation processes, giving rise to the extraordinary diversity known today. Large, succulent leaves typical of medicinal aloes arose during the most recent diversification ~10 million years ago and are strongly correlated to the phylogeny and to the likelihood of a species being used for medicine. A significant, albeit weak, phylogenetic signal is evident in the medicinal uses of aloes, suggesting that the properties for which they are valued do not occur randomly across the branches of the phylogenetic tree.ConclusionsPhylogenetic investigation of plant use and leaf succulence among aloes has yielded new explanations for the extraordinary market dominance of Aloe vera. The industry preference for Aloe vera appears to be due to its proximity to important historic trade routes, and early introduction to trade and cultivation. Well-developed succulent leaf mesophyll tissue, an adaptive feature that likely contributed to the ecological success of the genus Aloe, is the main predictor for medicinal use among Aloe species, whereas evolutionary loss of succulence tends to be associated with losses of medicinal use. Phylogenetic analyses of plant use offer potential to understand patterns in the value of global plant diversity.

The Global Taxonomy Initiative in Africa

The Conference of Parties (COP) to the Convention on Biological Diversity (CBD) has recognised the currently existing taxonomic impediment to ensure the conservation and management of the worlds biodiversity. In response, COP has formulated the concept of a Global Taxonomy Initiative (GTI) to promote a concerted effort among international funding agencies, national and sub-national governments, and non-governmental bodies. The GTI Africa Regional Workshop was held at the Kirstenbosch National Botanical Garden, Claremont, Cape Town, South Africa, from 27 February to 1 March 2001. The Workshop was attended by a total of 43 delegates, representing 32 countries (23 African) and 36 institutions or organisations. The Kirstenbosch Declaration was compiled during the Workshop and summarises the major decisions and proposals made by the delegates at the Workshop. A Final Report summarising the discussions and decisions from the GTI Africa Regional Workshop is being prepared and will be distributed to all interested parties. A taxonomic needs assessment for Africa has been conducted as part of this project. The results from this first ever comprehensive taxonomic needs assessment covering plants, animals and micro-organisms for the African continent as a unit, are reported on here and forms an important part of the Final Report. The needs assessment highlights the prominent taxonomic impediment currently existing in the continent. Taxonomic capacity building is urgently needed in Africa; therefore, African taxonomic institutions can benefit immensely from the Global Taxonomy Initiative.

Aloe arborescens (Asphodelaceae: Alooideae) and CITES

Abstract Following a formal request by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the appropriateness of the listing of Aloe arborescens Mill. (Asphodelaceae: Alooideae) in Appendix II of this Convention was assessed. As part of this assessment, the threatened (Red Data List) status in South Africa, the country within which it is taxonomically most diverse, was also re-assessed, and available information on formal and informal trade taken into account. Following a synthesis of the information available on A. arborescens, it is proposed that the species and its varieties should remain on CITES Appendix II, as their de-listing carries the risk of other Aloe species being traded under this name. It is retained in the Red Data List category for species of least concern (LC).

THE GENUS ALOE (ASPHODELACEAE: ALOOIDEAE) IN NAMAQUALAND, SOUTH AFRICA

Abstract Namaqualand stretches along the west coast of South Africa, from the Orange River in the north to the Olifants River in the south. It forms part of the Succulent Karoo, one of only two arid regions to qualify as a hotspot of global significance, and harbors an impressive array of succulents, geophytes and dwarf shrubs. Probably its most famous feature, however, is the mass display of flowering annuals and bulbs which appear after average or above-average winter rains. Aloes form a prominent part of the landscape throughout the distribution range of the genus, and Namaqualand is no exception. A total of 20 aloes occur in Namaqualand of which four (20%) are endemic to the area, with a further seven (35%) being near-endemic. A key to the aloes of Namaqualand is provided, as well as a short description, distribution map and information on habitat, flowering time, and conservation status for each of the species.

Aloes of the World: African Plants Initiative. An international webbased collaboration to promote scholarly research on Aloe L.

Summary: In November 2007, a group of about 40 international experts on the genus Aloe L. met in South Africa for a workshop to seek consensus on achievable, key objectives for the Aloes of the World Project (AWP). This was the first event of its kind where Aloe alone was approached on this scale. The Aloes of the World Project aims ultimately to compile as much information as is possible to facilitate internet-based scholarly research on the genus. The process and subsequent outcomes of the Pretoria workshop are discussed. Delegates acknowledged that an interim compromise may be achieved initially, where a minimum of essential elements are hosted on the Aluka (African Plants Initiative) website, with later upgrading of the information base in line with ongoing development of Aluka.

Aspects of the taxonomy of Aloe arborescens Mill. (Asphodelaceae : Alooideae)

Summary: Taxonomic concepts in the morphologically variable Aloe arborescens Mill. are discussed. Previous approaches to the taxonomy of this species varied from describing aberrant material as new entities, using formal taxonomic categories, to selecting forms with horticulturally desirable characters and naming these as cultivare. We propose that in the case of this species, the preferred approach to recognise variation among entities in horticulture should be at the level of cultivars, rather than formal taxonomic entities at infraspecific ranks. It is only after extensive fieldwork throughout the complete distribution range of this species and intensive research, including all possible forms of data (morphological, anatomical, chemical, molecular, etc.), that any formal distinctions at infraspecific level can be made.

The Genus Aloe L. (Asphodelaceae: Alooideae) in the Free State Province of South Africa

Abstract: The Free State Province of South Africa is situated virtually in the center of the country. It includes seven bioregions, and the vegetation consists mostly of grassland with some Karoo elements in the south. The Free State harbors 16 aloes, none of which are endemic to the province. A key to the aloes of the Free State is provided, as well as a description, distribution map and information on habitat, flowering time, and conservation status for each of the species.

Naturalised species of Agave L. (Agavaceae) in the Eastern Cape Province of South Africa

Summary: In alpha-taxonomic terms the Eastern Cape Province of South Africa, which includes the entire Albany Centre of Endemism, is one of the richest succulent plant regions in the world. The mild climate of the region is also suitable for the cultivation of a number of exotic succulents, several of which have escaped into the natural flora, subsequently becoming naturalised. The five species of Agave L. recorded for the Eastern Cape are here described and illustrated as part of compiling a Flora for the region. The species are Agave angustifolia Haw. var. angustifolia, A. americana L. var. americana, A. sisalana Perrine, A. vivipara L. var. vivipara and A. wercklei F.A.C.Weber ex Wercklé. A key is provided to assist with the identification of the five species.

Proposal to conserve the family name Asphodelaceae (Spermatophyta : Magnoliidae : Asparagales)

1 Biosystematics Research & Biodiversity Collections Division, South African National Biodiversity Institute, Private Bag X101, 0001 Pretoria, South Africa / Department of Plant Science, University of Pretoria, 0002 Pretoria, South Africa 2 Office of the Chief Director: Biosystematics Research & Biodiversity Collections, South African National Biodiversity Institute, Private Bag X101, 0001 Pretoria, South Africa / Acocks Chair, H.G.W.J. Schweickerdt Herbarium, Department of Plant Science, University of Pretoria, 0002 Pretoria, South Africa / Centre for Functional Ecology, Departamento de Ciências da Vida, Universidade de Coimbra, 3001-455 Coimbra, Portugal 3 H.G.W.J. Schweickerdt Herbarium, Department of Plant Science, University of Pretoria, 0002 Pretoria, South Africa Author for correspondence: Ronell R. Klopper, R.Klopper@sanbi.org.za

The Genus Aloe L. (Asphodelaceae: Alooideae) in the Eastern Cape Province of South Africa

Abstract The Eastern Cape is extremely diverse and is a climatic, topographic and geological transition zone. This transitional nature of the environment is reflected in the phytogeographical and phytosociological complexity of the Eastern Cape. The region has a very diverse flora comprising ca. 8 300 taxa (species and infraspecific taxa). A total of 39 aloes occur in the Eastern Cape of which ten (26%) are endemic to the area, with a further four (10%) being near-endemic. A key to the aloes of the Eastern Cape is provided, as well as a short description, distribution map and information on habitat, flowering time, and conservation status for each of the species.