Hydrophyllaceae R.Br.

Scientific Description

Common name. Waterleaf Family.

Habit and leaf form. Herbs (usually), or shrubs (sometimes spiny). Annual, biennial, and perennial; plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves. Mesophytic. Leaves alternate, or opposite; spiral; petiolate; non-sheathing; without marked odour, or foetid; simple, or compound; when compound, pinnate, or palmate (rarely). Leaf blades dissected, or entire; when simple/dissected, pinnatifid; pinnately veined, or palmately veined (rarely); cross-venulate. Leaves without stipules; without a persistent basal meristem. Stem anatomy. Nodes unilacunar. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous; via hymenoptera.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’ (usually), or solitary (rarely); in cymes. The terminal inflorescence unit cymose. Inflorescences ‘boragoid’ cincinni. Flowers often ebracteolate; regular; usually 5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk absent (usually), or present. Perianth with distinct calyx and corolla; (8–)10(–20); 2 -whorled; isomerous. Calyx (4–)5(–10); 1 -whorled; gamosepalous, or polysepalous (sometimes ‘lobes divided to the base’); imbricate; regular. Epicalyx present (as appendages between the calyx lobes), or absent. Corolla (4–)5(–10); 1 -whorled; appendiculate (often having scales inside the tube, alternating with the stamens), or not appendiculate; gamopetalous; imbricate, or contorted; rotate, or campanulate, or funnel-shaped; regular; blue, or purple, or white. Androecium (4–)5(–10) (as many as C). Androecial members adnate (to the corolla tube, and usually with basal appendages also united to the corolla, which in Hydrophyllum form tubes leading to the nectar); all equal, or markedly unequal; free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens (4–)5(–10); isomerous with the perianth; oppositisepalous (alternating with the petals); all alternating with the corolla members. Filaments variously, basally appendiculate. Anthers dorsifixed; versatile; dehiscing via longitudinal slits; introrse; appendaged. Gynoecium 2 carpelled. The pistil 1 celled, or 2 celled. Gynoecium syncarpous; synovarious to synstylovarious; superior (usually), or partly inferior (sometimes). Ovary unilocular, or plurilocular; 1 locular, or 2 locular. Gynoecium median; stylate. Styles 1, or 2; free, or partially joined; attenuate from the ovary; apical. Stigmas dry type; papillate; Group II type. Placentation when unilocular, parietal; when bilocular, axile. Ovules in the single cavity when unilocular, 2–100 (i.e. to ‘many’); when bilocular 2–50 per locule (i.e. to ‘many’); funicled, or sessile; pendulous (when funicled); epitropous; non-arillate; anatropous, or amphitropous.

Fruit and seed features. Fruit non-fleshy; dehiscent (usually), or indehiscent; a capsule, or capsular-indehiscent. Capsules when dehiscent, loculicidal (usually), or splitting irregularly, or septicidal (rarely). Seeds copiously endospermic. Endosperm oily. Cotyledons 2. Embryo chlorophyllous (1/1), or achlorophyllous (1/2); straight (spathulate or linear). Seedling. Germination phanerocotylar.

Physiology, biochemistry. Aluminium accumulation not found. Photosynthetic pathway: C₃.

Geography, cytology, number of species. World distribution: widespread. X = 5–13(+). 250 species.