Dr. Jeffrey M. Osborn

Publication Abstract

Osborn, J. M. and E. L. Schneider. 1988. Morphological studies of the Nympheaeceae sensu lato. XVI. The floral biology of Brasenia schreberi. Annals of the Missouri Botanical Garden 75: 778-794.

Observations conducted in East Texas on the pollination biology of Brasenia schreberi J.F. Gmel. confirm that anthesis is diurnal, with individual flowers opening and closing for two consecutive days. First-day flowers are morphologically and functionally pistillate. They are characterized by short, undehisced stamens and elongated, papillate stigmas that radiate outward over the perianths, providing an expanded surface area for pollen adherence. Second-day flowers are morphologically and functionally staminate. Staminal filaments are elongated, elevating the dehiscent anthers to a position above the centrally aggregated stigmas. Although self-pollination occurs, dichogamy prevents individual flowers from self-fertilizing. Notiphila cf. cressoni (Diptera; Ephydridae) was the most frequent insect visitor. Based on behavior and pollen loads, insect pollination is insignificant. The expanded stigmatic surface area, exerted stamens, and additional floral and vegetative features are adaptations for wind pollination. Data from pollen dispersal experiments indicate that anemophily is the primary mechanism of pollen transfer. This pollination mechanism is unique in the Nymphaeaceae sensu lato. Evidence from pollination biology, floral anatomy, seed anatomy, and embryology indicates a close evolutionary relationship between the Cabombaceae and Nymphaeaceae sensu stricto. Genera of the Nyumphaeaceae s. str.. and Nelumbonaceae exhibit a phyletic elaboration of the flower, whereas the Cabombaceae represent a phyletic reduction.

Aquatic plants, Brasenia, Cabombaceae, Nymphaceae, pollen, pollination