Shoreline Plants  

 
Species: Nasturtium officinale R. Br. Formerly called Rorippa nasturtium-aquaticum (L.) hayek, water cress
Family: Brassicaceae

This emergent perennial herb is typically observed as a tangle of stems and leaves growing in cold, flowing water. Usually the ends of the stems and the leaves are held above the water. The leaves are compound, each consisting of a central stalk with several round leaflets that have smooth or slightly wavy edges. The leaves have a strong peppery taste. The small flowers each have 4 white petals and are clustered at the ends of the stems.

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Leaf: The older leaves are compound, with each leaf consisting of 3 to 11 smooth or wavy-edged, oval or lance-shaped leaflets growing from a central stalk. The entire leaf measures 4 to 12 cm long, with the end leaflet usually larger than the others. Young leaves are simple, not compound.

Stem: The trailing, fleshy stem is 10-60 cm long, breaks easily, and is upright at the ends. It forms roots at the lower nodes.

Flower: White flowers appear above the water from March through October. The flowers are are clustered at the ends of the stems on short stalks. The flowers are 3-5 mm long and have 4 white petals.

Fruit: Thin, slightly curved, cylindrical pods are 10-25 mm long and about 2 mm wide, on stalks 8-12 mm long. The seeds are small (1 mm), round, and arranged in four rows inside the pods.

Root: Thin and fibrous. Roots often grow from the nodes of the the trailing stems.

Propagation: Rooting stem fragments and seeds.

Importance of plant: Eaten by ducks, muskrats, and deer. Widely used as a salad herb for its spicy, peppery flavor, it is grown commercially in the United States. It also contains high concentrations of vitamins and minerals. Water cress has a long history of medicinal use for a variety of ailments and was used during Roman times.

Distribution: Widespread in North America, Europe, Asia and South America. May have been introduced from Europe.

Habitat: Flowing streams and other shallow fresh water; prefers cold moving water.

May be confused with:  Western bittercress (Cardamine occidentalis), which typically has longer flower stalks (2-4 cm), a larger and wavy-margined terminal leaflet, and larger (2-3 cm) fruits. Western bittercress also grows in wet soil, but is not likely to be found in flowing water.

Photographs: Nasturtium officinale

Line Drawings: Nasturtium officinale


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