ABSTRACT
The papaya is a polygamous species of small semiwoody herbaceous trees indigenous in the eastern lowlands of Central America. Papaya trees are columnar in growth habit and superficially palm-like in appearance. They are unbranched or sparingly branched, and topped by a crown of leaves with long cylindrical hollow petioles and large palmately lobed pinnatifid blades. There are three sex forms of trees in C. papaya: hermaphrodite or bisexual, pistillate or “female”, and staminate or “male”. They are thought to be derived from an ancestral hermaphroditic prototype of which the present-day hermaphrodite may be a relict. Sex in C. papaya is determined by three homologous gene complexes on sex chromosomes. The hermaphrodite tree is believed to be a relict form of a perfect-flowered ancestral prototype of Caricaceae. The staminate flower is unisexual in that it lacks a functional pistil but has a full complement of stamens.
