A contribution to the embryology of the Verbenaceæ

Summary

Organogeny of the flower and structure and development of the anther and embryo-sac have been studied in some members of the Verbenaceæ. The development of the floral parts inStachytarpheta indica shows that the calyx differentiates before the stamens and the petals, and not after the stamens as has been described by Kanda (1923) inVerbena. Development of the anther and the pollen is quite normal. Cytokinesis takes place by furrowing. Tapetum is of the secretion type. The pollen grains are mostly spherical, but inStachytarpheta they are prominently three-lobed. The mature pollen grain is 3-nucleate. The ovule shows a single archesporial cell. No parietal cell is cut off and the archesporial cell directly develops into the megaspore-mother cell. A linear tetrad of megaspores is formed, of which the chalazal megaspore develops into the embryo-sac according to the normal type. The egg-apparatus has a normal structure and so is the behaviour of the polar nuclei. The antipodals are small and three in number, but inClerodendron Phlomidis they multiply by repeated divisions to form about twenty cells. The nucellus is of the typical sympetalous-type.