Journal article

Publication year: 1988

Pages: 293-320

Journal: Phyton: Annales rei Botanicae

Volume number: 28

Issue number: 2

ISSN: 0079-2047

Publisher: Institut für Biologie, Universität Graz, Austria) und Verlag Ferdinand Berger

Abstract: 
Poricidal anther dehiscence occurs in the majority of the species of the subtribe Cassiinae (Caesalpiniaceae); it imples a constraint for pollination through pollen-collecting female bees able to vibrate flowers. In open pollen-flowers, poricidal anthers also provide protection against pollen depletion by rainfall, as well as provide a means for more efficient and more economic pollination. The ovaries of the Cassiinae as also in the majority of the Fabales are elongated. It is shown that the longer the ovaries the more ovules they contain. The trend in the Cassiinae to approximate the position of the pollen releasing anther openings and the stigma is realized in different ways. In Cassia and many Senna species, at least some of the stamens are so long that the anther openings reach about the same level as the stigma. But there are also species, which bear flowers with all stamens much shorter than the gynoecium. In D. obtusifolia, for instance, the gynoecium is bent down to the anther openings. In several Chamaecrista species with short stamens only, a modified tube-like petal is formed, which functions as a prolongation of the stamens. Concomitantly, in all three genera there is a trend towards heteranthery and increasing zygomorphy of the flowers. In some cases these morphological constraints are accompanied by a trend for pollination by smaller bees towards a more effective pollination by larger bees, especially notable in the small-flowered Chamaecrista species with the tube-like petal. Structures for pollen protection and pollen economy were developed also by the Fabaceae. However, these parallel trends in evolution in Cassiinae and Fabaceae were attained on different morphological grounds.

Harvard Citation style: GOTTSBERGER, G. and SILBERBAUERGOTTSBERGER, I. (1988) EVOLUTION OF FLOWER STRUCTURES AND POLLINATION IN NEOTROPICAL CASSIINAE (CAESALPINIACEAE) SPECIES, Phyton: Annales rei Botanicae , 28(2), pp. 293-320

APA Citation style: GOTTSBERGER, G., & SILBERBAUERGOTTSBERGER, I. (1988). EVOLUTION OF FLOWER STRUCTURES AND POLLINATION IN NEOTROPICAL CASSIINAE (CAESALPINIACEAE) SPECIES. Phyton: Annales rei Botanicae . 28(2), 293-320.