Trees, shrubs, or clambering or twining lianas, rarely dioecious, unarmed. Raphides absent. Leaves opposite or occasionally in whorls of 3, with or usually without domatia; stipules persistent or caducous, interpetiolar, entire or 2-lobed. Inflorescences terminal and sometimes also in axils of uppermost leaves, cymose, paniculate, or thyrsiform, several to many flowered, sessile to pedunculate, bracteate. Flowers sessile to pedicellate, bisexual and usually distylous or rarely unisexual. Calyx limb 5-lobed nearly to base, frequently some or all flowers of an inflorescence with 1(-5) white to colored, petaloid, persistent or deciduous, membranous, stipitate calycophyll(s) with 3-7 longitudinal veins. Corolla yellow, red, orange, white, or rarely blue (Mussaenda multinervis), salverform with tube usually slender then abruptly inflated around anthers, or rarely constricted at throat (M. hirsuta), inside variously pubescent but usually densely yellow clavate villous in throat; lobes 5, valvate-reduplicate in bud, often long acuminate. Stamens 5, inserted in middle to upper part of corolla tube, included; filaments short or reduced; anthers basifixed. Ovary 2-celled, ovules numerous in each cell, inserted on oblong, fleshy, peltate, axile placentas; stigmas 2-lobed, lobes linear, included or exserted. Fruit purple to black, baccate or perhaps rarely capsular (M. decipiens), fleshy, globose to ellipsoid, often conspicuously lenticellate, with calyx limb persistent or caducous often leaving a conspicuous scar; seeds numerous, small, angled to flattened; testa foveolate-striate; endosperm abundant, fleshy.
Seeds numerous, pale brown to blackish, small, usually ± flattened, the surface reticulated.
Leaves petiolate, blades usually elliptic with an acute or acuminate apex, pubescent or less often glabrous.
Stipules entire to completely bilobed, persistent or caducous.
Shrubs, scandent shrubs or lianes.
Flowers usually yellow to red or sometimes white, occasionally sweet- scented, isostylous or heterostylous, borne in terminal panicles.
Calyx tube oblong, turbinate or ovoid; limb-tube small; lobes 5, usually subulate, linear, slightly spathulate or sometimes short and dentate or rounded, persistent or caducous; frequently several lobes on each inflorescence develop into a stalked white, creamy-yellow or sometimes red calycophyll (TAB. 73/A5).
Colleters usually present between the calyx lobes.
Corolla white, yellow or red; tube cylindrical, narrowly funnel-shaped or abruptly widened to accommodate the anthers, with flattened or fine hairs at the throat and between the anthers; limb 5-lobed, lobes reduplicate in bud, spreading at maturity, often with the centre portion connate, with short hairs and often a star-shape of longer, coloured hairs above.
Anthers 5, the tips just level with the throat or inserted up to halfway down the tube, linear, attached by very short filaments near the base; connective very shortly acuminate at the apex.
Ovary 2 (rarely 3–4)-locular; ovules numerous, inserted on fleshy placentas; style slender, sometimes divided into 2 arms; stigma included or occasionally exserted; lobes 2, ± oblong to fusiform.