Soursob Weed (Oxalis pes-caprae)
Common Names
Also known as African wood sorrel, Bermuda buttercup, buttercup oxalis, Cape cowslip, and Cape sorrel.
Description
Soursob is a low-growing, almost hairless plant with long-stalked, clover-like leaves. While often mistaken for clover, soursob is distinguishable by its heart-shaped leaflets, compared to clover’s oval-shaped ones.
Leaves and Stems
- Leaves grow from an underground stem (rhizome), just below or at the soil surface.
- Each leaf has three heart-shaped leaflets, 5–30 mm long, sometimes with brown or purple markings.
- Leaves fold downward at night or in low light.
Flowers
- Bright yellow, trumpet-shaped flowers appear in clusters of 3–25 at the top of stems.
- Each flower has five overlapping petals, ten stamens, and an ovary with five styles.
- Flowers open in sunny conditions and close at night or on cloudy days.
- Blooms from early winter to late spring (May–November).
Reproduction and Spread
- Primarily spreads through underground bulbs and bulbils (seeds are rarely produced in Australia).
- Bulbs are cone-shaped, white with brown scales, while bulbils are smaller and lack scales.
- Spread occurs through soil movement, garden waste, water, and animals such as birds.
Similar Species
There are about 30 species of Oxalis in Australia, with some appearing similar to soursob.