5661.000 Tristemma Juss.

Annual or perennial herbs or shrubs, with sharply 4-angular or -winged stems and branches. Leaves petiolate, opposite. Flowers 5-merous, sessile or subsessile, in terminal heads surrounded by leaves and leafy bracts; inner bracts coriaceous, chaffy or membranous. Receptacle ovoid or ovoid-oblong, glabrous or densely setose on the upper half or with 1–6 rings of bristles. Sepals persistent, reflexed, ciliate at the margin; petals mauve, pink or blue-violet, rarely white. Fruit a capsule 5-valved, with fleshy placentas, usually splitting irregularly. Seeds numerous, cochleate.

Worldwide: 15 species in tropical Africa, Madagascar and Mascarene Islands.

Zimbabwe: 1 taxon.