Watercress

Nasturtium officinale
(Rorippa nasturtium-aquaticum)

Photographed in Rackensack Canyon, Maricopa Co., Arizona, USA. April 2008.

ANNUAL: An aquatic annual found growing along mostly semipermanent waterways or close to springs. Plants rarely rise more than 8 cm above the water surface.

LEAVES: Leaves are pinnately compound with five or so leaflets. Margins are normally wavy-toothed. Young stems and leaves are edible - waterborne parasites like giardia are a concern, however.

RANGE: Introduced and widely cultivated; widespread in wet habitats across North America. Grows in wet soil at springs or in shallow water of slow moving streams. Homesteaders and early settlers often selected sycamore-lined waterways bringing with them seeds of watercress and other plants to cultivate.

FLOWERS: Many, compact flowers on mostly short spikes. Four white petals.

FRUIT: A turgid, oblong capsule with two rows of seeds.

UNARMED.

Several butterflies found flying within sycamore woodlands can use this plant as a larval host. These include the Sara Orange-tip (Anthocharis sara) and the Checkered White (Pieris protodice).

Brassicaceae -- Mustard Family

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More Information:

• USDA Plant Profile
• ITIS Taxonomic Report
• Google Images
• Google Scholar Literature Search