Branch apices, heterochrony, and inflorescence morphology in some mimosoid legumes (Leguminosae: Mimosoideae)

Abstract

Grimes, James (Harding Laboratory, New York Botanical Garden, Bronx, NY 10458 USA) 1996. Branch apices, heterochrony and inflorescence morphology in some mimosoid legumes (Leguminosae: Mimosoideae). Telopea 6(4): 729-748. Six species of mimosoid legumes, Paraserianthes lophantha, Zapoteca tetragona, Lysiloma microphyllum, Acacia nilotica, Ebenopsis ebano, and Pithecellobium dulce, are subjects of a study of morphology of inflorescences, branch-apices, and terminal and axillary buds. Differences in patterns of growth in the species can be attributed to shoot-dimorphism, phyllotaxy, and heterochronic differences in development of stipules and unit-inflorescences. Species form only long-shoots or one of two kinds of short-shoots. One kind of short-shoot is formed in a series from an axillary meristem, and is ephemeral if it produces inflorescences. The other is solitary and long-persistent. Inflorescences were found to be produced either on the long-shoots or the short-shoots, but not on both. All inflorescences can be described as pseudoracemes of unit-inflorescences, but differ depending on whether the unit-inflorescences arise from long-shoots or short-shoots, and on whether there is heterochronic development of unit-inflorescences and subtending leaves. The unit-inflorescences develop from primary buds or from secondary buds. Phyllotaxy is either spiral or distichous. Stipules arise either on the flanks of the leaf-primordium, or from primordia spatially independent, but concomitant with the leaf-primordium.