Oxalis pes-caprae

Oxalis pes-caprae earned itself a long string of common names, as widely prevalent and much noticed plants do. These include Cape sorrel, English weed, soursob and goat’s foot.

This did not happen as a result of it being considered royalty but the notoriety stemming from the plants invasive, weedy habits. In its natural habitat it is but one of many admired flowering plants that cause no problems.

In South Africa it grows coastally and some distance inland in the Western, Eastern and Northern Cape, restricted to the Mediterranean climate zone.

In many other countries this plant is branded as an unwelcome, damaging and costly intruder. These emigration destinations include the USA, Australia, southern Europe, Israel and Pakistan. Propagation does not only occur naturally through seed, but also vegetatively via bulbs that multiply in rhizome axils. Reports indicate that large tracts of land have been rendered useless for agriculture, causing stock losses. In southern Europe it grows densely under olive trees in some areas, causing difficulty to find olives on the ground where the traditional harvesting method still involves picking them up. 

The flower stalks are even sought after for enhancing the taste of a famous local dish, viz. waterblommetjiebredie. 

It might be interesting to discover the stories of how the more noxious weeds of the world bypassed immigration requirements or had been taken to new destinations by people meaning no harm. They were legally innocent in the days before the impact of species without natural enemies were realised or controls were introduced. These stories always involve human actions. By the time the full impact is felt in the host country, the culprit is usually dead.

Botanically the plant has the unusual feature of being tristylous or three-morphous. This means that three different flower structures occur naturally among plants within the species. The three forms do not cross-pollinate easily and the plants are not self-compatible.

The form that is common in Europe does not even propagate via seed, but only through forming more bulbs. The five petals of each flower are fused together at the base to form the pretty yellow corollas on their slender stems in winter and spring (www.europe-aliens.org; Manning, 2009).