Development of Dionaea Muscipula. I. Flower and Seed

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Abstract
The terminal bud of the short perennial rhizome forms a scape bearing a cyme of 2-14 actinomorphic, penta-cyclic flowers. The arrangement of the vascular bundles of the stamens is considered as further proof of alternipetalous and epipetalous whorls. When more than 10 stamens develop, the vascular bundle of one or more of the 5 epipetalous stamens is divided and supplies the additional stamen or stamens. The 4 microsporangia of each stamen develop in the usual manner. Prochromosomes are discernible in the early prophase of the microsporocytes. The 4 nuclei resulting from the 2nd meiotic division each have 15 haploid chromosomes. The mature pollen grains hang together in tetrads and each contains 6-8 large germ pores. The 5-carpellate paracarpous ovary develops numerous anatropous ovules on a basal placenta, with the tip of each slightly imbedded in a cup-shaped bolster of placental or receptacular tissue. The outermost layer of cells of the 2nd integument forms an outer seed coat of closely packed, radially elongated, heavy-walled, columnar cells; while the inner integument forms a lid overtopping the nucellus and is pushed off when the seed germinates. The single vascular strand extending to the chalazal end of each ovule does not turn or twist in its course. The outer layer of nucellar cells, except where it overtops the prothallial cells, increases enormously in radial dimension, surrounding a central strand of longitudinally elongated cells. By division of the single hypodermal archesporial cell, 2-3 layers of parietal cells are formed above the embryo sac. The formation and the development of the embryo sac and the endosperm show no unusual features. The mature seed contains a small basal embryo, consisting of 2 cotyledons and a short radicle surrounded by the cellular endosperm.

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