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
Male flowers
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)
Nomenclature:
Vallisneria
L.
Linnaeus: 1015 (1753)
Wright: 5 (1898)
Podlech: 4 (1966)
Lowden: 269 (1982)
Cook: 105 (1990)
Distribution & Notes:
Global
: Species 4, tropics and subtropics
Southern Africa
: Species 1:
Vallisneria aethiopica
Fenzl, N Namibia and Botswana; recently recorded from Lydenburg (Mpumalanga) and Cape Town (Western Cape), probably escapes from aquaria
Additional Notes:
Plant is totally submerged
Male flowers abscise and float on the water surface 'caught' by floating female flowers
References:
COOK, C.D.K. 1990.
Aquatic plant book
. SPB Academic Publishing, The Hague
LINNAEUS, C. 1753.
Species plantarum
. Laurentius Salvius, Stockholm
LOWDEN, R.M. 1982. An approach to the taxonomy of
Vallisneria
L. (
Hydrocharitaceae
).
Aquatic Botany
13
PODLECH, D. 1966.
Hydrocharitaceae
.
Prodomus einer Flora von Südwestafrika
142
WRIGHT, C.H. 1898.
Hydrocharideae
.
Flora of tropical Africa
7
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