Hydrocharitaceae

Abstract

Hydrocharitaceae, in order of Alismatales, is a monocotyledonous flowering plant family, including a number of species of aquatic plant, broadly called the tape grasses, containing the well-known Canadian waterweed (Elodea canadensis) and water thyme (Hydrilla verticillata), consisting of around 16 genera and approximately 135 species, and widely distributed in tropical and subtropical regions. The family includes both fresh water and marine aquatics in a wide variety of habitats. Plants are annual or perennial and floating or submerged. Stems are short or elongate and occasionally stoloniferous. Leaves are radical or cauline, whorled, opposite or alternate, and various shaped. Flowers are bisexual or unisexual, actinomorphic or zygomorphic. Stamens are one to numerous. Ovary is inferior. Fruit is a capsule. Seeds are exalbuminous with embryo upright. Three species, belonging to three different genera, are illustrated in this chapter.