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Ruppiaceae An aquatic, monocotyledonous (see MONOCOTYLEDON) family of submerged herbs, usually of brackish or salt water, that have linear or bristle-like leaves, sheathing at their bases, and short, terminal racemes of minute flowers. These have no perianths, 2 stamens, and an ovary of 4 or more free carpels which develop long, separate pedicels in the fruit, forming an umbel-like structure. Pollen grains are elongate in shape and rise to the surface in a ‘bubble’ of air, where pollination occurs. There is 1 genus, Ruppia, and about 7 species, occurring throughout temperate and subtropical regions, and in tropical mountain lakes.