POSLUSZNY, USHER1* and JEAN, M. GERRATH2. 1Department of Botany, University of Guelph, Guelph ON N1G 2W1, Canada; 2Department of Biology, University of Northern Iowa, Cedar Falls, IA 50614-0421. - Floral morphology and development in Rhoicissus digitata (Vitaceae).
As part of a continuing comparative study of floral development in the
Vitaceae, this paper describes the floral morphology and development
of Rhoicissus digitata(L.f.) Gilg & Brandt. Inflorescences in
this southern African species are small and cymose and arise in either
a terminal or leaf-opposed position. The five sepals are initiated
individually, but by maturity they appear as small teeth, as a result
of growth of a basal ring primordium. The five petals arise
individually in a position alternate to the sepals, and are thick,
green, valvate, and cucullate at maturity, with forked brown hairs on
their abaxial surface. The five petal-opposed stamens are initiated
more or less simultaneously, separate from the petals. The gynoecium
forms two chambers, each with two ovules. The pinkish, five-lobed
nectariferous disc arises from the base of the gynoecium. Fruits are
blue-black with purple juice at maturity, containing two or three
seeds with equal frequency. Floral developmental characters resemble
those found in Ampelopsisand Cissusmost closely, and
appear less derived than those of Vitis.
Key words: development, digitata, floral, morphology, Rhoicissus, Vitaceae