The Development of the Embryo Sac in the Convallariaceae

Abstract

1. In the eight members of the Convallariaceae investigated by the author, the embryo sac is formed from one reduction nucleus in Polygonatum, from 2 in Smilacina racemosa, S. amplexicaulis, and Streptopus roseus, and from 4 in Smilacina stellata, S. sessifolia, Maianthemum canadense, and Medeola virginica. 2. In all forms in which more than one reduction nucleus enters into the structure of the embryo sac, these nuclei are at first more or less completely separated by cell membranes, the degree of separation varying from split cell plates in Smilacina stellata to evanescent cell plates in Medeola virginica. 3. The difference in the degree of the separation of these cells cannot affect their morphological status; they are all megaspores. 4. In the light of this evidence it seems reasonable to conclude that all reduction nuclei arising from the nucleus of the megaspore mother cell, whether temporarily separated or not separated at all, should be regarded as megaspore nuclei. 5. Two megaspore mother cells were occasionally observed in six of the eight species investigated.