Aloe rupestorrens (Asphodelaceae), A New Pendulous Species from Northern Kenya

Eastern Africa boasts a high diversity of succulent plant species in general, and aloes in particular, perhaps only second to South Africa. The floristic uniqueness of the largely arid region of northern Kenya is indeed remarkable, especially due to the presence of several mountain peaks that are often referred to as “desert islands.” These peaks rise above the surrounding arid plains, creating isolated, cooler, and wetter environments that provide the much-needed microclimates for species to thrive. The genus Aloe, with its adaptation to xeric conditions, is among the top five succulent plant taxa that dominate northern Kenya's habitats. The Ngare Ndare riverine ecosystem presents a unique habitat in the Ngare Ndare Forest Reserve, Il Ngwesi Community Trust and the Lewa and Borana Wildlife Conservancies in which plants of a hitherto unnamed Aloe were found growing. Aloe rupestorrens is herein described as a new species growing along riverine cliff faces in the four localities. The plants are restricted to cliff edges by waterfalls and have not been seen in the general forested area away from the river, or along the riverbanks. Aloe rupestorrens is similar to the Tanzanian endemic Aloe flexilifolia with which it shares many morphological characters but differs in the size and distance between marginal teeth, inflorescence branching and petal color. Aloe rupestorrens is considered currently not at risk, as the three locations of occurrence are protected Wildlife Conservancies.