Morphology and Histology of Trevoa trinervis (Rhamnaceae), a Drougth Deciduous Shrub from the Chilean matorral

Abstract

Summary The ramification system and the histological structures of Trevoa trinervis, a shrub from the Chilean matorral, are studied. The axilar bud system of the principal branches is constituted by a summer bud that originates a thorn-shoot in the first year, and a winter bud. This remains dormant, to sprout rapidly as soon as the soil humidity increases during the following winter. The winter bud originates a small branch, bearing most of the leaves; its growth is completed by the development of a terminal inflorescence. When humidity decreases, both the branches and the leaves dry and drop. The leaves present a mesophytic structure. Several of the characters described are interpreted as adaptations to drought.