Plants, inflorescences and pollinators in the aquatic monocot Sagittaria trifolia L. (Alismataceae). A, Transplanted individuals in a pond bank. B, A raceme showing that female fl owers in lower whorls bloomed earlier than male fl owers in upper whorls. C, A solitary bee (Halictidae: Lasioglossum) collecting nectar and pollen from a male flower. D, The Lasioglossum bee pollinating female flowers. Photographed by Shuang-Quan HUANG. See HAN et al., pp. 379–385 in this issue.