Aquatic and Wetland Vascular Plants of the Northern Great Plains
58. Zannichelliaceae, the Horned Pondweed Family
1. Zannichellia L. -- Horned pondweed1. Zannichellia palustris L.
Monoecious, perennial, submersed aquatic, often forming extensive mats; stems thin and flexuous, densely leafy, freely branched from the base, anchored by roots, 0.5-5 dm long. Leaves simple, opposite, sessile, filiform, 1.5-6 cm long, ca. 0.5 mm wide; stipules membranous and soon disappearing. Flowers highly reduced, one staminate and typically 4(1-5) pistillate flowers at each node; perianth none; staminate flower consisting of a solitary anther raised on a short, slender filament; pistillate flowers located in the same or opposite the axil containing the staminate flower, sessile or short-peduncled as a group, surrounded by a cup-shaped, membranous bract, each flower comprised of a single fusiform carpel with a peltate stigma. Fruits often abundantly produced, drupelike, stipitate, mostly 2-4 per node, brown to reddish-brown, crescent-shaped, narrowly undulate to serrate on the keeled edges, 3-5 mm long, including the 1-2 mm long persistent style, ca. 1 mm wide. Jun--Aug. Fresh to brackish water of streams, reservoirs, lakes, ponds, marshes and ditches; common throughout; (Coastal and inland N.Amer.; also S.Amer., Eurasia and Africa).
 Zannichellia palustris. |
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