Oxalis pes-caprae

Oxalis pes-caprae is a tristylous flowering plant. Tristylous is a term referring to plants with heterostylous which indicates having different morphological types of flowers. Whereas it creates a self-incompatibility in fertilization. Meaning the pollen from one flower cannot fertilize another flower of the same morph.

In this case for Oxalis, tristylous refers to having three morphs. One morph has short pistils, and the stamens are long and intermediate; the second morph has the intermediate pistils, and the stamens are short and long, and the third morph has long pistils, and the stamens are short and intermediate.

Oxalis pes-caprae belongs to the Oxalidaceae family of plants. It is native to South Africa. In Afrikaans, it is called Suring. Oxalis pes-caprae is also known as Bermuda Buttercup, African Wood-sorrel, Bermuda Sorrel, Buttercup Oxalis, Cape Sorrel, English Weed, Goat’s foot, Sourgrass, Soursob, and Soursop.

Oxalis pes-caprae produces subterranean propagules. These are like bulbs. This variety has smaller bulbs than other African species. Oxalis pes-caprae is usually considered a weed and invasive in South Africa and other parts of the world.

Oxalis pes-caprae grows in sandy soil in warm dry locations and spreads easily. It is a perennial. It grows to about 20cm or 8in. tall.

It propagates through its underground bulbs. This is how it becomes invasive and hard to manage. Oxalis pes-caprae is called sour grass due to its sour taste and presence of oxalic acid.

The plant is edible but in smaller quantities, it is harmless to humans or livestock. In South Africa, it is used in Waterblommetjiebredie which is a stew. The bulbs are used in traditional medicine to treat tapeworm. The petals of Oxalis pes-caprae flower is used to create a yellow dye.