Otogeny of the embryo in Cornus florida L.

The zygotic embryo development in Cornus florida L. was documented during two growing seasons. Beginning at anthesis ovules of C. florida were sampled twice weekly. Anthesis was considered to be the time when one-half of the flower buds had opened and occurred near April 21 both years. The ovules were fixed, embedded, sectioned, and stained according to standard histological procedures for paraffin sections. Although several tissues sampled from four-to-five weeks post-anthesis revealed suspensor-like cells, the first tissues which contained recognizable embryos were collected six weeks post-anthesis. The globular embryo stage was completed three weeks later and most embryos had reached the torpedo stage by ten weeks post-anthesis. The embryos were anatomically fully developed and were accumulating storage material by July 30, fourteen weeks post-anthesis. At that time, fruits remaining on the tree were beginning to develop red coloration. Further embryo development was limited to continued storage substance accumulation and slight elongation with a final average length of 6.0 mm being reached by embryos collected in early October.