ABSTRACT: Field observations, carried out as part of a hydrodynamic study on submarine pollen dispersal in dioecious Amphibolis antarctica (Labill.) Sonder et Aschers. ex Aschers., showed that pollen release and subsequent pollination events occur in stages over a period of approximately 1 mo, from late October to early December, at 32* 16' S, 115* 41' E on the coast of Western Australia. Examination of the female flowers by scanning electron microscopy, during and after pollination events, showed that the filiform pollen had adhered to the stigmas. Our field observations of a subtidal (2 m below low water) A. antarctica meadow suggest that the pollen sacs dehisce whilst still attached to the male plant. Pollen is released slowly and takes on the approximate density of the seawater, and is then carried by the local coastal currents. No surface agglomerations of pollen were observed. Preliminary qualitative observations from a dye release study at the study site implied that pollen remained within the water column, close to and amongst the canopy, thus enhancing the likelihood of collision with the nearby female plants. This is the first account of in situ pollination of fully submerged subtidal A. antarctica.

KEY WORDS: Amphibolis antarctica . Filiform pollen . Pollen release . Hydrophily . Subtidal

Published in MEPS Vol. 133 (1996) on March 28
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1996