Common name. Raspworts. Family Haloragaceae.
Habit and leaf form. Shrubs, or herbs. Herbs annual, or perennial. Stem growth not conspicuously sympodial (monopodial). Helophytic to mesophytic. Leaves alternate, or opposite, or whorled; when alternate, spiral; 3 per whorl; petiolate, or sessile; non-sheathing; simple; epulvinate. Leaf blades entire; oblong, or ovate, or obovate, or linear, or orbicular; one-veined, or pinnately veined. Leaves without stipules. Leaf blade margins entire, or serrate. Leaf anatomy. Hairs present, or absent.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Anemophilous.
Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’ (rarely); in fascicles. The terminal inflorescence unit racemose. Inflorescences axillary; inflorescence an indeterminate raceme or spike, flowers in the axils of alternate primary bracts, lateral spikes arising in the axils of upper leaves; pseudanthial, or not pseudanthial. Flowers pedicellate; bracteolate, or ebracteolate (bracteoles rarely replaced by 4 hairs); minute to small; regular; (2–)4 merous; cyclic; tetracyclic, or pentacyclic. Free hypanthium absent. Perianth with distinct calyx and corolla; 6, or 8; 2 -whorled; isomerous; free. Calyx present; 3–4; 1 -whorled; polysepalous; valvate; exceeded by the corolla; regular; persistent. Sepals ovate, or triangular (deltoid). Corolla present; 3–4; 1 -whorled; polypetalous; regular. Petals usually shortly clawed; hooded; not navicular. Androecial members definite in number. Androecium 8. Androecial members free of the perianth; all equal; free of one another; 1 -whorled, or 2 -whorled. Androecium exclusively of fertile stamens, or including staminodes. Staminodes 4. Stamens 4 (when staminodes present), or 8; all more or less similar in shape; isomerous with the perianth, or diplostemonous; oppositisepalous, or alternisepalous and oppositisepalous; filantherous (with rather large anthers). Anthers basifixed; non-versatile; dehiscing via longitudinal slits; latrorse; four locular; tetrasporangiate. Gynoecium (2–)3–4 carpelled. The pistil 1–4 celled. Gynoecium syncarpous; synovarious; inferior. Ovary plurilocular; incompletely 3–4 locular. Epigynous disk absent. Gynoecium stylate. Styles 3–4 (the same in number as the sepals); free; apical. Placentation apical. Ovules 1 per locule; pendulous; anatropous.
Fruit and seed features. Fruit non-fleshy. Pericarp crustaceous with no septa. Fruit indehiscent; a nut; 1 celled; 1 locular; 1 seeded. Seeds more or less copiously endospermic. Endosperm oily. Cotyledons 2. Embryo straight.
Special features. Inflorescence indeterminate.
Etymology. From the Greek for "angle, corner" and "fruit", referring to the ribbed fruit.