Watercress
Nasturtium officinale
Family · Brassicaceae · Poisonous
Read this before the sheet
This plant, or one that resembles it, is dangerous. Identifying is not authorising: no app has the authority to tell you that you may eat or touch a plant.
Emergency
The fleshy-leaved, peppery-tasting plant growing in running water, eaten since antiquity. The risk is not in the plant: it is in the water and in the neighbours.
Streams and ditches · Fields and pasture
Also known aswatercress, yellowcress
How to tell it
Hollow fleshy stems lying in the water and rooting at the nodes. Leaves divided into three to nine leaflets, the end one clearly larger and rounded, which is the decisive mark. Small white four-petalled flowers in a cross. A distinctly peppery scent when a leaf is rubbed between the fingers.
What it is confused with
Hemlock water dropwort
Oenanthe crocata
They grow in the same stream and it is the confusion that kills in Portugal. Watercress has white four-petalled flowers in a cross and a large round end leaflet; hemlock water dropwort has minute flowers in an umbel, leaves divided two or three times, and yellow tubers at the root. If the flower is an umbel, it is not watercress.
Fool's watercress
Helosciadium nodiflorum
Fool's watercress has all leaflets alike and flowers in an umbel; watercress has a much larger end leaflet and four-petalled cross flowers. Fool's watercress is not poisonous, but it is the middle step of the confusion that ends at hemlock water dropwort.
What it is for
It has been eaten for centuries in soups and salads and is a commercial crop. Gathered from a stream it carries two real risks: fascioliasis, a liver parasite carried by larvae that attach to the leaf in water where livestock graze, which cooking solves and washing does not; and the neighbouring hemlock water dropwort, which kills. This guide says recognise it, not gather it.
Traditionally used as food. This is not permission to eat it.
With documented traditional uses. Not a therapeutic indication and not a dose.
Where it occurs
Each square is an area with recorded observations of this plant. The lighter background is the set of areas where any of the entries has been observed, and serves as a reference. Note what this is not: it is not where the plant lives, it is where people record it, so trails and towns always look fuller than the mountains. Data from GBIF.
Sources
Community
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