Floral histogenesis in the Monocotyledons. IV. The Liliaceae

Abstract

An account is presented of floral histogenesis in Bulbine bulbosa R.Br. and Stypandra glauca R.Br. The apex of the floral axis in both species has a two-layered tunica, and bracts arise through the periclinal division of cells of the inner layer of the tunica (hypodermis). In Bulbine, axillary flower primordia are initiated in the periclinal division of subhypodermal cells; in Stypandra the flower primordia are terminal and arise directly from the apices of branches of the inflorescence. In both species the perianth'members originate, in the same manner as the bracts, through periclinal divisions in cells of the hypodermis. Periclinal divisions may occur in the cells of the outer tunica layer (dermatogen) after the prinlordia are well formed. Divisions in subhypodermal cells in the area of perianth initiation are associated with the formation of a provascular strand and it is doubtful if such divisions contribute anything to the tissue of the perianth primordium itself. The stamens are initiated in the periclinal division of both hypodermal and subhypodermal cells. In Bulbine the carpels develop through periclinal divisions in the hypodermis and dermatogen. The placentas appear to arise through divisions in subhypodermal cells as structures adnate to the carpels. In Stypandra the carpels arise in a quite different manner through the periclinal division of subhypodermal cells. The margins of the carpels develop as the placentas and there is no suggestion in the early ontogeny of the gynaecium that the placentas have an independent origin.