Watercress (Nasturtium microphyllum/officinale)
Kingdom: Plantae
(Unranked): Angiosperms
(Unranked): Eudicots
(Unranked): Rosids
Order: Brassicales
Family: Brassicaceae
Genus: Nasturtium
Species: Nasturtium microphyllum/officinale
Common names: Watercress, Kowhitiwhiti ,Brooklime, Cress, Cresson, Nasturtium, Water Cresses,
The 2 species jointly listed above are almost indistinguishable without examination of the seed capsule.
Watercress was introduced into NZ by the French as a food plant. It is a fast-growing, aquatic or semi-aquatic, perennial herb native from Europe to central Asia, and one of the oldest known leaf vegetables consumed by human beings. These plants are members of the Family Brassicaceae or cabbage family, botanically related to garden cress, mustard and radish — all noteworthy for a peppery, tangy flavour.
It is found growing in open running watercourses or near cool shallow springs, freshwater drains and streams
This marginal aquatic plant, can grow in water up to 6m in depth (Waikoropupu springs).
Watercress differs from all other mustards by its alternate, pinnately compound leaves with 3-11 oblong to oval leaflets, shiny, dark green, rounded at the tip, smooth, without teeth or with wavy-toothed margins. It has creeping hollow floating stems, succulent or fleshy, smooth, with fibrous roots, rooting occurs anywhere along the submerged stem mostly at the nodes.
Watercress produces small, white flowers in terminal racemes and in racemes from the axils of the uppermost leaves. The 4 petaled flowers bloom November to February.
Maori rapidly incorporated watercress into their diet as a boiled green, preferring it to the introduced garden cabbage. One can gather the edible fresh green leaves anytime. Avoid plants growing in water that drains from fields where animals, particularly sheep, graze. Due to the risk of watercress being infested with the deadly liver fluke parasite, if unsure, cooking the leaves will destroy any parasites and render the plant perfectly safe to eat.
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