Oxalidaceae

Abstract

Perennial, rarely annual herbs, sometimes succulent, often with underground storaging bulbs, tubers or rape-like roots, or shrubs, small trees, or sometimes vines; nodes trilacunar. Leaves alternate, often clustered, digitate or pinnate, rarely unifoliolate, the terminal leaflet lacking in Biophytum, leaflets articulate; petiole usually well-developed, sometimes expanded into blade-like phyllodium, or woody and persistent, at the base and insertion of the blade articulated; stipules present or not. Inflorescences thyrso-paniculate, with monochasia or dichasia in spike-like, umbellate or capitate arrangement, or racemes. Flowers regular, perfect, usually heterotri(di)stylous, or plants androcioecious (Dapania), rarely cleistogamous and apetalous; calyx lobes 5, quincuncially overlapping, the three external ones often much larger, all persistent in fruit; petals 5, mostly contortly overlapping, free or often postgenitally united at the base above the free claws, caducous, white, red, violet to purple or yellow, never blue; stamens obdiplostemonous, antepetalous stamens shorter than antesepalous or sterile (Averrhoa p. p.); filaments united at the base in an annulus; anthers introrse with small connective protrusion; nectaries outside the base of antepetalous stamens (actually at the level of a short androgynophore); ovary superior; carpels 5, antepetalous, united to form a 5-locular ovary; placentas axile or rarely parietal (Oxalis aberrans); stylodia always distinct, stigmata capitate or punctiform; ovules 2 per locule, rarely more, anatropous, bitegmic, crassinucellate or tenuinucellate, with endothelium, the micropyle directed upwards, slit-like (Averrhoa and Biophytum) or funnel-shaped (Oxalis) with chalazal appendages. Fruit a loculicidal, sometimes fleshy capsule, or a 5-ribbed berry. Seeds with straight embryo and fleshy endosperm, aril-late in Dapania.