Fls small, us. solitary in lf-axils, (3)-4-(5)-merous; sepals or calyx lobes us. 4; petals us. 4; stamens as many as petals. Carpels us. 4, free or nearly so; ovules 1 to several per carpel; style us. short. Scales 4-2-0. Fr. of follicles. Small slender ± succulent herbs with small opp. lvs connate at or near base. Subcosmopolitan genus with c. 60 spp. Of the N.Z. spp. , , have a wider distribution, the rest are endemic.

Annual or perennial herbs, subshrubs or shrubs. Lvs opposite, simple, entire or sometimes crenately toothed, usually spaced along stems, often decussate, sometimes subrosulate, connate at base or free, sometimes small and scale-like. Infl. terminal or axillary, of loose or compact cymes forming a corymb or thyrse, sometimes 1-few-flowered. Fls 4-5-(12)-merous, erect or spreading in bud. Sepals free or slightly connate at base, equal. Petals free or slightly connate at base, sometimes lower part fused to form a tube, fleshy, often spreading and corolla star-like, usually white, pink or red, rarely yellow. Stamens as many as petals, in 1 whorl, free or almost so, included or exserted. Scales free, very variable in shape. Carpels free, (4)-5-(12). Seeds usually numerous, occasionally 1-few.