Source:
SSA
Description:
Submerged, freshwater, herbaceous, grass-like, glabrous, perennial, +/- stemless aquatics, forming runners, dioecious. Leaves rosulate, radical, linear, up to 2 m or more long, sheathing at the base, with 3-9 parallel veins and faint transverse veinlets, margin denticulate, apex obtuse. Inflorescence axillary; spathe of 2 united bracts. Maleflowers very small, many, shortly pedicelled, maturing consecutively, becoming detached as buds, floating and expanding after reaching surface of water; sepals 3, ovate, convex; petals 3, minute; stamens 1-3, divergent. Female flowers axillary; solitary, tubular, bilobed; peduncle long, reaching surface (if not too deep), spirally contracted after anthesis; sepals 3, ovate or oblong-ovate; petals 3, minute; ovary 1-locular, with 3 parietal placentas bearing many ovules; styles 3, bilobed. Fruit fusiform, breaking irregularly. Seeds many, ellipsoidal, up to 2 mm long. x = 10, 12 (7, 8, 9-1 report each) (polyploidy).
Distribution:
Species 4, tropics and subtropics; 1 in sthn Afr.: Vallisneriaaethiopica Fenzl, N Namibia and Botswana; recently recorded from Lydenburg (Mpumalanga) and Cape Town (Western Cape), probably escapes from aquaria. Plant is totally submerged; male flowers abscise and float on the water surface 'caught' by floating female flowers.
Classification:
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