Aquatic botany ELSEVIER Aquatic Botany 59 (1997) 253-262 Developmental morphology of the androecium and gynoecium in Ruppia maritima L." considerations for pollination Christian R. Lacroix *, James R. Kemp Department of Biology, Universi O"of Prince Edward Island, 550 University A~,enue Charlottetown. Prince Edward Island, Canada CIA 4P3 Accepted 28 June 1997 Abstract Ruppia maritima, widgeon grass, is an aquatic angiosperm common in salt marshes. Although previous studies have covered general aspects of pollination and floral development, little information is available on the functional aspects and development of the androecium and gynoecium in relation to pollination. Using the techniques of scanning electron microscopy and thin sectioning, this study focuses on the functional morphology of the gynoecium, anthers, and pollen grains. The funnel-like arrangement of the carpels directing pollen to the stigmatic regions. the buoyancy offered by presence of stomates and underlying spongy tissue in the carpellary outgrowth, the boomerang-like morphology of the pollen grains which facilitates their aggrega- tion, and the sheath enclosing the anther are examined from the perspective of this specialized. hydrophilous pollination system. © 1997 Elsevier Science B.V. Keywords: Hydrophily; Carpellary outgrowth; Pollen; Anther; Stomates; Development; Functional morphol- ogy 1. Introduction Ruppia maritima L., widgeon grass, is an aquatic angiosperm usually found in brackish waters of relatively high salinity. In the province of Prince Edward Island in Canada, R. maritima is commonly found in salt pans, also known as Ruppia pools, in intertidal salt marshes. Various specific aspects of the pollination and developmental * Corresponding author. Tel.: + 1 902 566 0974; fax: + I 902 566 0740; e-mail: lacroix@upei.ca 0304-3770/97/$17.00 © 1997 Elsevier Science B.V. All rights reserved. Pll S0304-3 770(97)00074-0