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.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0291-7) contains supplementary material, which is available to authorized users.

The predominantly southern African Xanthorrhoeaceae subfam. Asphodeloideae (Asphodelaceae subfam. Alooideae) has long been regarded as comprising seven so-called alooid genera (Aloe, Astroloba, Chortolirion, Gasteria, Haworthia, Lomatophyllum, Poellnitzia). A reassessment of the classification of the traditionally broadly circumscribed genus Aloe, a charismatic Old World group of leaf succulents, has necessitated nomenclatural adjustments. We propose a narrower generic concept for Aloe s. str. and the recognition of segregate genera to reflect accumulating evidence for monophyletic groups: here, the genus Kumara is reinstated and the new genera Aloidendron and Aloiampelos are established. New combinations are made in Aloe for the three species of Chortolirion.

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 world's 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 sub­national governments, and non­governmental 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 micro­organisms 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.