Oxalis hirta L.
Common names: hairy oxalis (Eng.); suring (Afr.)
A vigorous, easy-to-grow, ornamental Oxalis with branched stems and attractive magenta-pink flowers in winter and spring.
Oxalis hirta is a geophyte which grows in winter and is dormant throughout the hot, dry summer, characteristic of the Mediterranean climate in the Western Cape. The rootstock is a small, conical bulb.
It has a leafy, often branching stem, 50 to 300 mm tall. The leaves are trifoliolate (in threes), grey-green; the leaflets are linear to obovate and hairy underneath. The branches and leaves are initially upright, but tend to flop over as they lengthen. The whole plant is softly hairy.
The flower stalks arise from the upper leaf axils, in autumn and early winter (April to June). The flowers are magenta red to violet purple, mauve or white, with a yellow tube.
This species is assessed as Least Concern (LC) and is endemic to South Africa.
Distribution and habitat
Oxalis hirta can be found in the Western Cape, from the Bokkeveld Mountains to the Cape Peninsula, where it grows on sandy flats and lower mountain slopes.
Derivation of name and historical aspects
The name Oxalis comes from the Greek oxis, which means ‘acid’, referring to the sour-tasting sap of some species. The species name hirta means ‘hairy’.
The genus Oxalis is a large genus of about 700 species spread throughout the world, with about 270 species in southern Africa. The habitats where members of Oxalis are found, vary from fynbos, grassland, forest, wetlands, and moist, disturbed places, waste places, along watercourses, roadsides, and rocky hillsides, clayey or sandy soils.
This bulb can be found in rocky slopes and open ground in the Mediterranean climate region of South Africa, which has a cool, rainy winter and a hot, dry summer. The plants die back in early summer, and are dormant during the hot, dry summer. They sprout again in autumn, and grow and flower in winter and early spring.
The plant can be used as an ornamental. Although no hazards are known for Oxalis hirta, other species of Oxalis contain oxalic acid and are poisonous to humans and livestock if consumed in large quantities.
Growing Oxalis hirta
Oxalis hirta is easily grown in well-drained soils in filtered sun to partial shade and it needs occasional irrigation, but avoid watering during its summer dormant season. Grow them in rock garden pockets or in containers.
Propagation is usually from the bulb offsets that are separated during repotting. Replant in late summer.
Seeds will only be produced if 2 clones are present and in order to harvest the seeds, a fine net should be tied around the capsules for several days. Sow seed as soon as it is ripe. Seedlings grow fast and should flower in their second year.
This plant does not suffer from many diseases or pests, but sometimes when humidity is high, powdery mildew can be seen and when the foliage is wet, aphids can sometimes attack the new growth. Caterpillars and scale may also become a problem.
- Duncan, G. 2010. Grow bulbs. A guide to the cultivation of bulbs of South Africa and neighboring countries. Kirstenbosch Gardening Series. South African National Biodiversity Institute, Cape Town.
- Foden, W. & Potter, L. 2005. Oxalis hirta L. var. hirta. National Assessment: Red List of South African plants version 2017.1. Accessed on 2020/01/02.
- Goldblatt, P. & Manning, J. 2002. Cape plants: a conspectus of the Cape flora of South Africa. Strelitzia 9. National Botanical Institute, Pretoria and Missouri Botanical Garden, St Louis.
- Leistner, O.A. (ed.). 2000. Seed plants of southern Africa: families and genera. Strelitzia 10. National Botanical Institute, Pretoria.
- Retief, E. 2004. Oxalis. L. (Oxalidaceae). PlantZAfrica. Online. http://pza.sanbi.org/oxalis
Free State National Botanical Garden
Plant Type: Bulb
SA Distribution: Western Cape
Soil type: Sandy, Loam
Flowering season: Autumn, Winter
PH: Acid, Neutral
Flower colour: Purple, White, Pink, Yellow, Mauve/Lilac
Aspect: Full Sun, Morning Sun (Semi Shade), Afternoon Sun (Semi Shade)
Gardening skill: Average