Embryogeny of Species of Podocarpus of the Subgenus Stachycarpus

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Abstract
Pronounced differences are found in the appearance and organization of the early embryos of P. spicatus, P. ferrugineus, and P. usam-barensis. All 3 spp. have 7-12 binucleate embryonic cell units. These units give rise to groups of cells which usually combined to form a single embryo; thus simple polyembryony prevails within this group. The embryogeny of these 3 spp. suggests a sequence of evolutionary steps which appears to be opposite to the sequence suggested by study of the external morphology of the seed cone[long dash]the reduction series from a loose strobilus to a stalked ovule. Causal morphology may explain the modifications in the development of the embryo as due to changes in the shapes of the archegonia. No apical initial cell could be observed at any stage in the development of the embryo of any of the spp. The resemblances between the embryos of Cephalotaxus and those of certain podocarps are superficial and do not suggest close phylo-genetic connections. In P. jerrugineus and P. usam-barensis the stem tip meristems are organized and recognizable between the cotyledons of the embryos before the seed is mature.

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