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Graminae
Common names
Swamp rice grass, swamp cut grass (southern Africa), lambedora
grass (Venezuela).
Description
A scrambling, stoloniferous perennial with leaf-blades 5-13
mm wide, and growing to 40-60 cm high. Leaves bright green, very rough
and unpleasant to handle. Spikelets like rice, but much smaller. They are
scabrid and often strongly flushed with brick-red or orange, an unusual
colour in grass spikelets. Panicle branches are nearly always zig-zag,
at least after the spikelets have fallen (Chippendall & Crook, 1976).
Distribution
Throughout the tropics and subtropics.
Season of growth
Perennial.
Altitude range
Sea-level to 2 200 m.
Rainfall requirements
It grows in a rainfall regime from 750-5 000 mm, in swamps.
Drought tolerance
It survives well into drought until the swamps dry out.
Soil requirements
It generally grows on heavy-textured clay soils in swamps and
valley bottoms.
Suitability for hay and
silage
It makes quite good hay but is difficult to harvest from swamps
and is usually cut when swamps dry out.
Toxicity
In Zambia, scouring occurs when cattle move from the fibrous
forest grazing to the rich plains grasses consisting of Echinochloa pyramidalis,
E. scabra, Acroceras macrum, Hemarthria altissima, Leersia hexandra and
Vossia cuspidata, and it may be three to four months before they regain
condition (Verboom & Brunt, 1970).
Latitudinal limits
About 30°N and S.
Palatability
Palatable when young, but eaten when old if there is a scarcity
of feed. Its sharp edges may make it less acceptable.
Natural habitat
Swamps and dams and ditches in standing water, or as floating
grass islands as in Logtak Lake, Manipur, India.
Tolerance to flooding
Excellent. It is an aquatic grass. In Suriname it occurs in
creeks, ditches and swamps, in paddy fields, and on some drier clay soils
(Dirven, 1963a).
Genetics and reproduction
2n=48 (Fedorov, 1974).
Economics
Leersia hexandra is pan-tropical in its occurrence and is one
of the mostly highly regarded of the swamp grasses for grazing, particularly
in the dry season. In the Llanos Inundables of Colombia and Venezuela it
is the second most important food of the giant rodent, the capybara (Hydrochoerus
capybara), and comprises 29.16 percent of the diet during the rainy season,
15.25 percent at the end of the rains, and 7.74 percent at the end of the
dry season (Escobar & Gonzalez, 1976).
Animal production
In the Venezuelan llanos the pasture consists of Panicum laxum,
Leersia hexandra and Hymenachne amplexicaulis (68 percent) with Eleocharis
mutata and bushes as minor components. At the lowest stocking rate of 1.6
capybaras per hectare a decrease in P. Laxum occurred. At three beasts
per hectare a further decrease in P. Laxum occurred with an increase of
Leersia hexandra and weeds. At six beasts per hectare both L. hexandra
and P. Laxum declined and weeds and pioneer species increased (Ojasti,
1976). It is an important pasture grass for cattle, but no cattle performance
data have been found.
Further reading
Dirven, 1963a; Talapatra, 1950.
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