Wild Watercress (Nasturtium officinale)

There’s no shortage of watercress at supermarkets. The leafy green, with its distinct peppery flavour, is most often used raw in salads and sandwhiches. Wild watercress (Nasturtium officinale) packs slightly more of a punch than the commercially-grown variety and can be found growing from autumn to late spring in the winter rainfall areas of South Africa. Native to Europe and Asia, the introduced plant frequents waterways where flowing, slightly alkaline water passes through. Locally, it is most often found choking mountain streams, rivers and other tributaries. 

The characteristic clumps of leaves are wild watercress’ biggest key identifier. When young, rosette-like shoots emerge from where the previous year’s growth died back after flowering. This new stage of growth provides the best eating experience, and due to recency, there’s a reduced risk of contracting liver fluke, which is explained in detail further below. Like other members of the mustard family, the leaves are hot and spicy, a bit like horseradish. In terms of storage, the shelf life of the harvested tops of this plant is relatively short, but they will keep for several days in a bowl of clean water, with the water being replaced every day. Wilting will occur once the tops have been removed from the water.

Wild watercress is extremely nutritious. The leafy greens are packed with Vitamin K, not the most common vitamin yet responsible for blood coagulation and the binding of calcium on our body. Other vitamins contained are C, B1, B2 and E. In addition, flavonoid antioxidants such as carotene, lutein and zeaxanthin are found in wild watercress, which support good eyesight and provides cell damage protection from free radicals. The herb is a warming stimulant with its hot flavour.

After successful identification of wild watercress, it’s important to note that the leaves will taste more hot and bitter if gathered during late spring leading up to summer. This is when the flowering cycle occurs and the resulting flavour is less pleasant. Gather the fresh shoots during early winter. While this plant can reside in polluted waterways, only those growing in clean water should be gathered for the table. 

Special attention should be paid to the following when gathering wild watercress.

Never gather this wild edible where cattle graze. Liver fluke is a nasty parasite that can spend part of its lifecycle fastened to the leaves of wild watercress in areas where cattle are kept. Belonging to the group of parasitic flatforms, adult flukes can reside in the livers or bile ducts of its host, usually cattle. From within the host, the adult fluke will lays its eggs which will pass out through the animal’s faeces and hatch into a larval form. If this material gets its way to water, the larvae will swim around and infect water snails, and once it has caught a ride with a snail, the larva will develop until it is ready for the next stage of its life. At this point it will develop into several young ‘cysts’ which will eventually leave the snail host. These cysts will attach themselves to plants growing in the water such as grass or watercress, where they encyst. The life cycle is completed when the plants containing the fluke cysts are eaten by a host. These cysts reach maturity after travelling through the bloodstream to the gut and eventually liver. 

Cattle may be treated with success, but to humans liver fluke is a dangerous parasitic illness that can be fatal. It is on record that some people have passed away in South Africa from eating raw, wild watercress which contained liver fluke. Two ways to eliminate risk of contraction is to only cut the parts of wild watercress above the waterline, and cooking the leaves, which kills bacteria and parasites. 

This website takes a sustainable approach to foraging and doesn’t focus on protected or indigenous plants or fungi. Like the other invasive plants on this website, this is a species that should not be cultivated or propagated in South Africa. It’s often illegal to buy, sell or trade in exotic plants.

Learn how to forage with this South African foraging guide, or find out which South African books cover foraging

Other wild edible plants to forage in South Africa