Abstract
Abstract The arborescent taxa ofDracaenawhich form the dragon tree group comprise five species found in Macaronesia, Morocco (D. draco), East Africa (D. ombet,D. schizantha), Arabia (D. serrulata) and the island of Socotra (D. cinnabari). A new species of dragon tree,Dracaena tamaranaeA. Marrero, R.S. Almeida & M. Gonzalez-Martin, is described from Gran Canaria, Canary Islands. This new species differs fromD. draco, the only otherDracaenaspecies currently known in Macaronesia, in having a growth form and inflorescence type and leaves more similar to the East African and Arabian species ofDracaena. In contrast,D. dracoappears to be related toD. cinnabari. In this paper, we also present a study of the taxonomy, habitat and ecology of all the species of the dragon tree group. These are found in thermo-sclerophyllous plant communities of tropical–subtropical regions which are rather xerophilous and have a rainfall range of 200–500 mm. Our study indicates two independent colonization events forDracaenain Macaronesia. In addition, we suggest that the dragon tree group provides an example of two major biogeographical disjunctions between East and West Africa. We postulate that this group has a Tethyan origin, a hypothesis supported by fossil and palaeoclimatic data, and thus parallels the distribution and dispersal pattern of other taxonomic groups.
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