Ontogeny of palmately compound leaves in angiosperms: 1.Tabebuia pentaphylla Hense

Abstract

The palmately compound leaf ofTabebuia pentaphylla is initiated by periclinal division in the hypodermal layer at the flank of the maximal shoot apex, which lacks cytohistological zonation. The growth of the leaf primordium is diffuse until it reaches a height of 50–60 μm after which an adaxial meristem makes it conspicuously thick at the basal region. The first pair of lateral leaflets arise about 50 μm below the tip of the leaf primordium when the latter is about 150 μm high and before the differentiation of a well defined marginal meristem. The second pair of leaflets arises subsequently below the first. The terminal portion becomes the central leaflet. The sites of leaflet initiation are the terminal endings of acropetally differentiating procambial strands. The 6-layered plate meristem of the leaflet lamina arises from a marginal meristem whose submarginal initial is wedge shaped. Leaflet venation is comptodromous and the ultimate areoles lack free vein endings.