Abstract
In Acnistus arborescens (Solanaceae), a tropical, alternate-leaved arborescent species, the shoot apex is made up of a tunica of two byers, a third being recognizable at the ma:úmum arca stage, a fbttened. corpus and a medullar meristem, leaf primordia originate in a numbcr of peridinal divisions in the T II layer followed by periclinal, antidinal and oblique divisions in the cells dcrived and in the corpus and by exclusively antidinal divisions in T I. Tbe primordium apical cells divide repeatedly to form a thumb-shaped foliar axis in which acropetal procambiwn differentiation occurs and from which petiole and midrib derive.
Marginal meristems, made up of marginal and submarginal initials, give me guite early to the foliar protoderm and laminar mesophyll respectively. Prevalence of anticlinal divisions in the lattle leads to the f1attening of the lamina. Divisions crease last in the adaxial layer of submarginal initial dcrivates, which gives rise to the palisade parenchyma.