Shrub, glabrous or puberulous, foetid when bruised, stem and branches circular. Leaves opposite, generally lanceolate, attenuate, membranous; stipules broad, acute, persistent. Inflorescence terminal and axillary, 3-fid, shortly peduncled or sessile clusters or subcapitulum. Flowers white or purplish, dimorphic, bracteate and bracteolate, bracteoles 2, cuspidate, forming an involucre or scarious tube. Calyx-tube obconic, included in the involucre of bracteoles, lobes (4-) 5 (-6) short, persistent, elliptic-ovate or rotundate, cilliate. Corolla infundibular; tube slender, hairy within, throat glabrous, narrow; lobes valvate in bud, ovate (4-) 5-(6), cuspidate, inflexed. Stamens (-4) 5 (-6), inserted on the corolla throat filaments very short, anthers linear or oblong, exserted or included, dorsifixed. Disc depressed. Ovary 5-locular, one ovule in each locule; style filiforn; stigma 5-lobed, lobes linear, exserted or included. Capsule subcylindrical, oblong, or ovoid, 5-locular at apex and 5-valved at base, spliting into 5, erect, free, fibrous pyrenes. Seeds erect, linear, testa membraneous.