Comparative flower and fruit structure in the Colletieae (Rhamnaceae)

MEDAN, DIEGO; AAGESEN, LONE

BOTANISCHE JAHRBUCHER FUR SYSTEMATIK, PFLANZENGESCHICHTE UND PFLANZENGEOGRAPHIE

E. Schweizerbart'sche Verlagsbuchhandlung

Año: 1995 vol. 117 p. 531 - 564

0006-8152

We comparatively studied flowers and fruits of nearly all 20 species of Colletieae, and of the related genera Noltea and Ceanothus. Flower structural data at microscopic level are offered for the first time for Adolphia, Kentrothamnus, Noltea, Trevoa and Retanilla, and expanded for Ceanothus, Colletia and Discaria. Apart from identifying core attributes for the tribe, we analysed 25 characters showing inter- and intrageneric variability. Overall, gross morphological results are coincident with those of taxonomic monographers; however, we detected serveral traits related to stamen, stigma and aril that, although still neglected in taconomic use, allow generic distinction. Within the tribe a trend seems to exist towards increased flower depth, which is linked with (1) increased flower size, (2) a progressive association with specialized pollinators, (3) a tendency for the nectary to become extended over the flower tube or sepatated from its bottom and, sometimes, with (4) the development of structures supporting reverse herkogamy and secondary pollen presentation. And independent trend to progressive loss of fruit dehiscence is associated to (1) increasing complexity of diaspores and, in part, to (2) increased fruit size.