Description

Key Characters:

Growth Form: Small shrubs to small trees, rarely scrambling to semi–climbing.

Stems: Branches terete (cylindrical), quadrangular, or 4–winged, hairy or glabrous.

Roots:

Leaves: Leaves simple. Opposite. Margins entire or rarely toothed. Petiolate to sessile. Stipules interpetiolar, may also be intrapetiolar.

Flowers: Flowers in inflorescences terminal (subg. labordia), axillary, ramiflorous, or cauliflorous, monadic, triadic, dichasial, botryoidal, and occasionally thyrsoidal, accessory axes may be present, often umbelliform or glomerulate. Flowers bisexual (perfect) or functionally unisexual, actinomorphic. Calyx 5-merous, sepals united at base, lobes imbricate in bud, inner surface of calyx often with colleters at the base, margin mostly fimbriate. Corolla 5-merous, campanulate to rotate, white, often with yellow or green tinge, outer surface glabrous to short–hairy, inner surface glabrous to densely pilose, hairs (when present) in throat, mouth, and often extending on to lobes, sometimes also near the base of the tube; lobes imbricate or contorted in bud. Stamens 5, alternipetalous, attached to mouth of corolla, exserted, usually recurved after anthesis, glabrous or hairy; filaments mostly short; anthers 2-celled, introrse, connective often extended to form an apical appendage; anthers dithecal, opening by longitudinal slits. Ovary superior or partly inferior, carpels hairy or glabrous, 2– or 3-locular, sometimes partitions imperfect in upper part of ovary; ovules numerous, amphitropous, placentation axile; style terminal, mostly short; stigma clavate, ellipsoid, to globular, sometimes ± oblong, about as large as ovary.