Embryological Studies in Euchresta japonica (Leguminosae)

Abstract

Embryological features in Euchresta japonica, a species of the monotypic tribe Euchresteae, are described for the first time. Features in microsporogenesis are as follows: the anthers are tetrasporangiate; anther wall development corresponds to the dicotyledonous type; the tapetum is of the glandular type and uninucleate; the microspore tetrad is tetrahedral. Pollen grains are 2-celled at the time of shedding. These features are common with those generally found in Papilionoideae to date. Features in megasporogenesis are as follows: the archesporium is one-celled and hypodermal; the ovule is bitegmic, campylotropous and crassinucellate; one megaspore mother cell forms a linear tetrad. Megagametogenesis is of the Polygonum type; the antipodals are very ephemeral and most of the polar nuclei are in contact with each other and fused before fertilization. These embryological features of Euchresta show that the tribe Euchresteae is distinct from related tribes Sophoreae and Thermopsideae and may suggest that it is an advanced tribe related to Sophora and Maackia.