Morphology of the American Holly Shoot and Inflorescence1

Abstract Morphological examination of the vegetative bud of American holly, Ilex opaca Ait., shows it to consist of an apical meristem surrounded by leaf primordia and these in turn by fleshy cataphyls (bud scales). With expansion of the bud into a shoot, flower buds are initiated in the axils of cataphyls and a few leaf primordia. When flowers are not initiated in the leaf axils, vegetative buds develop therein and in the terminal of the shoot. The male inflorescence is a cyme with 3 flowers and the female inflorescence a solitary flower. Both staminate and pistillate flowers normally have 4 sepal points, 4 petals, 4 anthers and 4 carpels though 5 and 6 of each are frequently observed in individual flowers. Pistillate flowers bear no pollen and staminate flowers have only a rudimentary pistil. The trimerous primordium, though variously shaped, is the origin of leaves, cataphyls, resting vegetative buds, bracts, the calyx, and the inflorescence. Differentiation into leaves or cataphyls and inflorescences or resting vegetative buds appeared to be controlled by the physiological condition of the plant at the time of differentiation.