The fruit, a kind of pome, consists of a specialized stem which surrounds a normally 2-carpelled but 1-ovuled ovary. It matures dry, and dehisces along 4 parenchymatous rays and at the surface of the carpels. It includes the true fruit, which is a nut formed by the lignification of the exocarp into a hard shell surrounding a single, loose, 2-lobed orthotropous seed, the embryo of which has bifurcated and folded cotyledons oriented transversely to the septum. The cupule is a specialized stem and may be regarded as a cup-shaped receptacle of 4 sectors. Its vascular system (in transverse section) consists of 4 segments of tissue, in which can be discerned an outer and an inner ring of bundles, dissected into 4 groups by parenchymatous rays. The outer ring is a section of an outer vascular cylinder normally oriented, and from it the sepal bundles, and 2 groups of bundles extending to the tips of the stigmas, diverge near the top of the cupule. The remaining bundles of the outer cylinder extend inward and then downward, so that an inner cylinder of reversely oriented bundles is formed. At the base of the cupule they are directed upward again, so that a third cylinder of bundles, normally oriented, is formed, from which 2 dorsal carpellary bundles diverge. The remaining bundles are the septal bundles which supply the orthotropous, sessile, ovule.