IT appears that not one of the Apocynaceae, a family of about iooo species, has ever been studied carefully in reference to the minute morphology of the flower. Considering this in connection with the fact that the family stands near the Asclepiadaceae, with their peculiar pollen and stigma, it was believed that it deserved investigation. Buds and flowers of Apocynum androsaernijolium L. were collected in various stages, and the results of their investigation are herewith described.The order of appearance of the floral whorls is centripetal. The calyx shows no peculiarities other than a ruffling of the epidermis on the abaxial surface near the base, suggesting a mechanism for the folding of the sepals.Each petal of the campanulate corolla has on its inner surface near the base a ridge ( fig. i, r) running from the midrib diagonally outward and toward its base. It is highest at the midrib, and undoubtedly functions as an aid in compelling cross-pollination. The ridge arises from the more superficial cells of the leaf, and does not affect the course of the veins. Its meristematic crest forms the cells for its enlargement.The stamens are peculiar in form, adjusting themselves neatly in a ring rather closely applied to the stigmatic head ( fig. i, s). At the base of each are two long auriculate appendages (figs. I, 2, 3, ap) extending downwards dorsal to the filament. The sporangia are above the insertion of the filament, and do not extend into the appen- forming a ring around the stigmatic head (figs. I, 2, b). These hairs meet similar ones from a ring around the head, thus preventing pollen from rolling into the base of the flower. dages. The loculi open on their inner surfaces, somewhat laterally, by longitudinal slits, and immediately beneath them is a beard of epidermal hairs extending transversely across the faces of the anthers, I905] 49This content downloaded from 044.224.250.