Northern Prairie Wildlife Research Center
Aquatic and Wetland Vascular Plants of the Northern Great Plains
52. Hydrocharitaceae, the Frog's-bit Family
1. Elodea Michx. -- Waterweed
2. Elodea longivaginata St. John
Stems terete, sparsely branched, 3-10 dm long. Leaves all decussate
or some lower ones in whorls of 3, linear, 5-20 mm long, 0.5-2 mm wide, acute
to obtuse. Spathes of male flowers 2-15 cm long, inflated near the summit,
to 2.5-4 mm wide; male flowers peduncled by the threadlike hypanthium
which is up to 30 cm long; sepals elliptic, 3.5-5 mm long; petals
white, linear, 5 mm long; stamens 9, all attached at the summit of the
hypanthium. Pistillate spathes linear-cylindric, 3-7 cm long; female
flowers extended by the elongate, threadlike hypanthium which may attain
lengths of several dm; sepals elliptic, 2.8 mm long; petals white,
4 mm long; stigmas entire, 1.5 mm long. Capsules ovoid, 10 mm
long; seeds cylindric, 6 mm long. Jul--Aug. Prairie ponds, lakes and
reservoirs; uncommon and scattered, c and w ND, e MT and e WY; (ND to Alta.,
s to NM and UT).
Previous Section -- Elodea canadensis L. C. Rich.
Return to Family -- Hydrocharitaceae
- The Frog's-bit Family
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