Family: Oxalidaceae

Widely distributed, the largest number of species come from South Africa and South America, although this genus also contains the ubiquitous weeds of American gardens, ornamentals and perennial, tuberous or bulbous plants. They have tripartite leaves which fold up at night, a caustic sap with a sour taste, and spring or summer flowers. All of the weed species produce many bulbils, from which they are generally propagated.

Species

O. adenophylla, zone 5, has pink or mauve flowers.

O. carnosa, zone 10, a succu­lent from Chile and Bolivia, grows to 10 cm (4 in) high. It has a tuberous root, thick, fleshy stems which become woody and somewhat gnarled, and yellow flowers in groups of three or four.

O. gigantea, zone 9, from Chile, is a succulent shrub, to 2 m (6 ft) high, covered in fine hairs. It has drooping side branches, oval leaf lobes and yellow flowers.

O. hirta, zone 9, has bright pink flowers in winter.

O. lobata, zone 8, produces bright yellow flowers in late summer and autumn.

O. pes-caprae, soursob, zone 9, is a stemless perennial. The leaves are gener­ally marked with small, purple spots and the flowers are yellow. It is a common weed of cereal crops in some countries.

O. purpurea 'Alba', zone 8, has large silky white flowers in winter. There is also a burgundy-leaved form of O. purpurea with striking, hot pink flowers.

O. succulenta, zone 9, a succulent from Chile and Peru, has a short, thick-branched, scaly stem and small, deciduous leaflets on thick, fleshy stalks. Many small, yellow flowers grow on the forked stalks. Some of the more attrac­tive oxalis species worthy of cultivation include O. adenophylla, O. hirta, O. lobata and O. purpurea.

Cultivation

Grow the bulbous and tuberous species in sandy soil in full sun, and keep dry during the winter resting period. Because some of these species can be invasive, it is a good idea to contain them by growing in pots. Propagate the bulbous and tuberous species from the ripe seed which is expelled with great force from the seed capsules. The tuberous-rooted types can be grown from the bulbils they produce in spring or summer.

Climate

There are species suited to various cli­matic zones.