Floral histogenesis in the monocotyledons. I. The Gramineae

The pattern of floral histogenesis in a representative species from each of six tribes of the Gramineae is shown to be similar to that described in a previous communication for Triticum. Periclinal division of sub-hypodermal cells characterizes the origin of spikelet, flower, and stamen primordia. Periclinal divisions also occur in hypodermal cells during flower and stamen formation; and such divisions are more frequent at stamen initiation than at the initiation of flower primordia. Periclinal division of dermatogen cells never occurs during the formation of these organs, but is, on the other hand, a constant feature in the formation of glumes, lemma, palea, lodicules, and carpel. The hypodermis always contributes to the tissues of the glume and lemma primordia; it less frequently contributes to the tissues of the lodicule and palea, and only occasionally to that of the carpel. The morphology of the gramineous flower is discussed on the basis of floral histogenesis and the pattern of prorascular tissues in the gynaeceum. The literature dealing with floral histogenesis and the pattern of prorascular tissues in the gynaeceum.