Latin Name:Nasturtium officinale; syn. Nasturtium microphyllum, Rorippa nasturtium-aquaticum
Family Name: Brassicaceae
Like all the brassicas, Watercress should be fed in moderation as it contains goitrogens which interfere with the thyroid if eaten in excess.
Although cases are rare, it is recorded that tortoises have developed liver flukes (a type of parasitic worm calledFasciola hepatica) from eating Watercress contaminated with trematodes and picked from the wild -- often from stagnant, rather than free-flowing, water. These trematodes are ingested when the tortoise eats the particular species of mud snail that is acting as host for the worm. Infection is more common in aquatic turtles than in tortoises, and although flukes can be eliminated with medical treatment, it is best to ensure that watercress is fully washed and examined before feeding, and avoid picking the plant if it is growing in stagnant water. See also Watercress in the Fruit and Vegetable category.
Please be aware that two or more goitrogenic plants should not be fed in conjunction with each other, and the sum total of goitrogenic foods should not exceed the guideline for a single plant of 'in moderation' (amber-green) or 'sparingly' (amber-red). This will ensure that goitrogenic consumption stays within safe limits.