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Aquatic and Wetland Vascular Plants of the Northern Great Plains

52. Hydrocharitaceae, the Frog's-bit Family

1. Elodea Michx. -- Waterweed

1. Elodea canadensis L. C. Rich. in Michx.

Stems terete, often freely branched, 2-5(10) dm long. Lower leaves opposite, reduced, ovate-lanceolate; middle and upper leaves in whorls of 3, linear-lanceolate (on male plants) or oblong-lanceolate to ovate-lanceolate (on female plants), 5-15 mm long, 1-5 mm wide, mostly more than 1.5 mm wide, obtuse-apiculate, more strongly overlapping on pistillate plants. Winter buds appearing as short, compact branches in late summer. Spathes of male flowers borne in upper axils, ca. 15 mm long, inflated upward to 4 mm wide; male flowers peduncled by the threadlike hypanthium which is 3-20 cm long; sepals elliptic, 3.5-5 mm long; petals white, clawed, linear, 5 mm long; stamens 9, the inner 3 uplifted on a common stalk. Spathes of female flowers borne in upper axils, cylindric, 10-20 mm long; female flowers extended to the surface by a threadlike hypanthium 2-28 cm long; sepals oblong-elliptic, 2-2.2 mm long; petals white, oblanceolate, ca. 2.5 mm long; stigmas 2-cleft, 4 mm long. Fruit ovoid, ca. 6 mm long; seeds narrowly cylindric, 4.5 mm long, glabrous. Jun--Aug. Quiet water of streams and reservoirs; occasional in e and c parts of our region and the Black Hills, otherwise scattered w; (Que. to B.C., s to NC, AL, AR, OK, CO, UT, NV and CA; intro. in Europe). Anacharis canadensis (Michx.) Rich.
Elodea canadensis, male and female plants.
GIF- Distribution Map

Map key

Return to Family -- Hydrocharitaceae - The Frog's-bit Family
Next Section -- Elodea longivaginata St. John

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