THE DOMINANT ROLE OF THE EPIDERMIS IN LEAVES OF ADIANTUM

Abstract

the fertile ovule lies in the locule of the carpel opposite, not in the locule of its own carpel. Vestigial ovules are usually present in the abortive carpels and are usually absent in the carpel containing the fertile ovule. The carpel with the welldeveloped locule, therefore, is usually sterile, though it contains the single fertile ovule in the flower. The vascular supply of the ovary consists of five peripheral bundles and a central bundle. The central bundle usually divides in the vicinity of the ovule attachnent, primitively, into three ventral bundles and an ovular bundle. Reduction stages occur in the various species showing the loss of one, then both sterile ventral bundles, followed eventually bv the disappearance of the fertile ventral bundle. The ovular bundle mav be double at its origin, but it fuses before entering the ovule. The ovular supply, therefore, like that of the fertile ovules in the Linnaeeae, is douHle. Some species show vestiges of ovular traces to some of the abortive ovules. Lateral and dorsal carpellary traces for the three carpels are variously derived from the peripheral and central bundles. Four of the peripheral bundles divide at the top of the ovary. In all, ten bundles are formed,-five petal traces, five stamen-sepal bundles. In manv of the species, flowers occur with no fertile ovule, though one abortive ovule is relatively betterdeveloped than the rest. The supply is simnilar to that of the normal ovary. The relatively welldeveloped abortive ovule is delimited in the upper part of the ovary around thee ovular bundle in the center. It emerges in the center of a 3-lobed locule which contains even more reduced vestigial ovules attached to the three placentae. It is evident that there has been enlargement and atrophy of organs, and adnation and cohesion of parts and their vascular supply in the evolution of the genus. Reduction stages are found in the dorsal and marginal carpellary supply; the supply to fertile and abortive ovules; the number, position, and development of abortive ovules; the peripheral bundles; and the sepal traces. Comparative study of the internal morphology and vascular anatomy of the flower indicates that V. Sieboldii is the most primitive; FT. Opulus, the most advanced. Also primitive are V. Cartes i, V. Lantana and V. dentatum. More advanced are V. rhitidophyllum, V. cassinoides, V., acerifolium, V. tri.lobum anid others.