Abstract Detail

Development and Structure

Hayden, W John [1], Fagan, Camille [2].

Anatomy and Pollination of Subterranean Cleistogamous Flowers of Benghal Dayflower (Commelina benghalensis, Commelinaceae).

Anatomy and pollination of subterranean cleistogamous flowers of Benghal Dayflower (Commelina benghalensis) is described as a contribution to understanding its reproductive biology. Specimens studied were found on the University of Richmond (VA) campus in October 2012 as weeds among ornamental plants, the first recorded population of this federally listed noxious weed in Virginia. Plants were collected to local extinction and were rendered as herbarium vouchers and anatomical specimens preserved in formalin-acetic acid-ethanol for anatomical study. Whereas above-ground chasmogamous spathes bear multiple flowers, subterranean stems bear one spathe per node, each enclosing a single cleistogamous flower. Only the three anterior stamens produce functional pollen; the posterior three stamens are staminodes, present merely as much-reduced filaments. Tapetum is amoeboid and endothecium is present. The three-carpellate superior ovary bears five dimorphic orthotropous ovules. Nearly mature flowers have straight to somewhat curved styles; at maturity, styles elongate and coil. The subterranean cleistogamous flowers and the spathes which envelop them remain closed throughout flower and seed development. In most cases for which the details are known, pollination in cleistogamous flowers involves germination of pollen grains in intact anthers, producing pollen tubes that eventually grow through the anther wall to the stigma. In contrast, our observations indicate that coiled style growth in mature subterranean flowers of C. benghalensis causes physical rupture of anthers, thus bringing pollen into direct contact with stigmas. Pollen tubes were observed only in styles that had previously undergone coiling; numerous pollen tubes were observed within mucilaginous secretions of the mature stylar canal. The subterranean cleistogamous flowers of Benghal Dayflower and their apparently unique mode of pollination, viewed together with reproductive capacity of its aerial chasmogamous flowers, underscore the complexity and flexibility of the reproductive biology of this troublesome weed species.

1 - UNIVERSITY OF RICHMOND, DEPT OF BIOLOGY, 28 WESTHAMPTON WAY, RICHMOND, VA, 23173, USA
2 - University of Richmond, Department of Biology, 28 Westhampton Way, Richmond, VA, 23173, USA

Keywords:
cleistogamy
Commelina benghalensis
Commelinaceae
pollination.

Presentation Type: Oral Paper
Session: 49, Developmental and Structure II
Location: 205/Savannah International Trade and Convention Center
Date: Wednesday, August 3rd, 2016
Time: 4:45 PM
Number: 49005
Abstract ID:464
Candidate for Awards:None