Tropical-Alpine Life-Forms of Vascular Plants

Abstract

The alpine flora of the high East African mountains is renowned for its Giant Senecios, Giant Lobelias, and other weird growth forms. Detailed studies of this afroalpine flora have led to a description of five life-forms of vascular plants, the morphological peculiarities of which are interpreted as ecological adaptations to the tropical-alpine climate with recurrent night frosts throughout the year. The same life-forms occur under similar climatic conditions in other tropical high mountains, notably in the South American Andes. A comparison was made between tropical-alpine life-forms and temperature conditions of Africa and South America. The results support the hypothesis that those life-forms result from parallel adaptive evolution responding to extreme environmental conditions. The crucial factor seems to be the low night temperatures, and most morphological specializations can be interpreted as adaptations favouring temperature insulation and the maintenance of the water balance.