The Embryo Sac of Erythronium americanum

Abstract

The ovary is trilocular, each locule containing 2 rows of anatropous, bitegmic ovules. One of the subepidermal cells of the nucellus enlarges and functions directly as the megaspore mother cell. Normally only 3 divisions intervene between the megaspore-mother-cell stage and the 8-nucleate sac; thus the development is of the Adoxa type. The chromosome number is n = 24 and 2n = 48. Some embryo sacs show an unusual organization which indicates that occasionally the development may be of the Fritillaria type. Numerous intra-ovarial pollen grains were found. These, like other pollen grains, usually showed a degenerating vegetative nucleus and a large spherical generative cell with deeply staining cytoplasm and prominent nucleus.