Floral developmental morphology of Persea americana (Avocado, Lauraceae):: The oddities of male organ identity

A floral developmental series was determined for Persea americana (Lauraceae, avocado), and the floral morphology of this species was compared with available data for other members of Persea. We compared the structure of the inflorescence and flower with that of vegetative shoots with respect to phyllotaxy and leaf shape. The inflorescence is a determinate thyrse (panicle) with variable numbers of lateral branches. Staminal glands in Persea may represent abaxial-marginal emergences rather than stamens. However, these glands are occasionally involved in transitions to pollen sacs and ovary margins. Stigmas, pollen sacs, staminal appendages, glands of staminodes, and margins of tepals share features that are subjectively associated with "androecia.'' In the innermost androecial whorl, staminodial glands appear united because of the reduction of the middle portion to a staminodial apex. The apex of staminodes is homologous to the filament and anther, as well as to the stigma of the carpel, and corresponds to the connective tip in other basal angiosperms. In Persea, the connective and the staminode apex also correspond to the body of the tepal (i.e., all but the margin). Above a constriction (stipe), the carpel forms a cross zone bearing the single ovule; this cross zone also corresponds to the thecae in stamens, similar to observations for other basal angiosperms.