ABSTRACT
The various dry inter-Andean valleys in Bolivia are identified and characterized in terms of topography, climate and vegetation. The distribution of the families Labiatae, Asclepiadaceae and Acanthaceae in Bolivia is analysed. All three families show high levels of endemism in Andean Bolivia and, in particular, in the dry inter-Andean valleys. However, the floristic affinities of the different families vary considerably, making generalizations about floristic composition of the valleys difficult. In Labiatae, the species occurring in the dry valleys are principally from genera with an essentially Andean distribution. In the case of Asclepiadaceae and Acanthaceae, there are significant chaco and cerrado elements. Genera and families with an amphitropical distribution show stronger links with the Argentinean flora. Disjunct distributions give only weak support for the Pleistocenic arc thesis. High levels of endemism imply the need for more protected areas.
