Herbs annual or perennial [rarely epiphytic or subshrubs]. Stems erect or procumbent, usually succulent, often rooting at lower nodes. Leaves simple, alternate, opposite, or verticillate, not stipulate, or sometimes with stipular glands at base of petiole, petiolate or sessile, pinnately veined, margin serrate to nearly entire, teeth often glandular-mucronate. Flowers bisexual, protandrous, zygomorphic, resupinate to through 180° in axillary or subterminal racemes or pseudo-umbellate inflorescences, or not pedunculate, fascicled or solitary. Sepals 3(or 5); lateral sepals free or connate, margins entire or serrate; lower sepal (lip) large, petaloid, usually navicular, funnelform, saccate, or cornute, tapering or abruptly constricted into a nectariferous spur broadly or narrowly filiform, straight, curved, incurved, or ± coiled, swollen at tip, or pointed, rarely 2-lobed, rarely without spur. Petals 5, free, upper petal (standard) flat or cucullate, small or large, often crested abaxially, lateral petals free or united in pairs (wing). Stamens 5, alternating with petals, connate or nearly so into a ring surrounding ovary and stigma, falling off in one piece before stigma ripens; filaments short, flat with a scalelike appendage inside; anthers 2-celled, connivent, opening by a slit or pore. Gynoecium 4- or 5-carpellate, syncarpous; ovary superior, 4- or 5-loculed, each locule with 2 to many anatropous ovules; style 1, very short or ± absent; stigmas 1-5. Fruit an indehiscent berry, or a 4- or 5-valved loculicidal fleshy capsule, usually dehiscing elastically. Seeds dispersed explosively from opening valves, without endosperm; testa smooth or tuberculate.
Two genera and more than 900 species: mainly in tropical and subtropical Africa, some species in temperate Asia, Europe, and North America; two genera and 228 species (187 endemic, two introduced) in China; three additional species (all endemic) are of uncertain placement.
All but one of the species in the family belong to Impatiens. The unispecific Hydrocera is confined to India and SE Asia.
Chen Yiling. 2001. Balsaminaceae. Fl. Reipubl. Popularis Sin. 47(2): ii-vii, 1-243.
