Aquatic and Wetland Vascular Plants of the Northern Great Plains
22. Brassicaceae, the Mustard Family
3. Nasturtium R. Br. -- Watercress1. Nasturtium officinale R. Br.
Glabrous, fibrous-rooted, perennial aquatic; stems rather lax and trailing in water or on mud, freely rooting from lower nodes, erect or ascending toward the tips, 1-5 dm long. Leaves 4-13 cm long including the short to long petiole, 2-5 cm wide, pinnate or sometimes the earliest ones simple with only the terminal leaflet present; terminal leaflet ovate-cordate to subrotund or obovate, often much larger than the elliptic to obovate lateral leaflets, entire or weakly crenate. Racemes 1-several per stem, flat-topped and elongating in fruit. Sepals greenish-white, oblong, the outer pair saccate at the base, 1.5-2.5 mm long; petals white, sometimes tinged with purple, obovate, 3.5-5 mm long. Siliques linear, often curved, 10-25 mm long, ca. 2 mm thick, subterete, tipped with a short, truncate style beak 1 mm or less long; seeds in 2 rows in each cell of the fruit, conspicuously areolate. Jun--Oct. Springs and streams where water is fresh; e and sw SD and NE, especially common in streams of the Black Hills; (Intro. from Eurasia and established throughout most of the U.S. and s Can.). Rorippa nasturtium-aquaticum (L.) Hayek.
This plant is the watercress of commerce and is often used as a salad green.
 Nasturtium officinale. |
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