Broad-leaved Carpet Grass

Axonopus compressus (Sw.) P.Beauv.

Family: Poaceae.

Names:

Broad leaved Carpet grass.
Other Names:
Flat Jointgrass
Savannah grass

Summary:

A perennial, stoloniferous, carpet forming, hairless grass. 150-600 mm tall.

Description:

Cotyledons:

One

Leaves:

Hairless but there may be a few hairs where the blade joins the sheath and along the edge of the blade.
Blade - Flat or keeled. Striped. Narrowly egg shaped to parallel sided. 80-250 mm long x 60-120 mm wide. Flattened and folded along the obvious midrib. Rarely with hairs on the upper side, never hairs on the lower side, hairs on the edges.
Ligule - short membranous rim that is flat on top and is usually fringed with fine hairs.
Sheath - flattened, keeled. Striped. Often have a purple tinge. Edges are translucent. Deeply split. Hairless or rarely hairy on the edges.
Auricles - None.

Stems:

Slender or in tufts. 1-3 nodes. Nodes are densely hairy.
Flattened. Often purplish. Nodes often hairy.

Flower head:

Main axis (rachis) is triangular with concave faces giving 3 distinct lengthwise ridges. Usually 2 or 3 branches, with the upper 2 paired and one longer than the other.
Spikes - 2 or 3 usually (less than 5). No stalk. Slender. Erect or spreading. 40-100 x 1-15 mm.

Flowers:

Spikelets - Single, one flowered. Oval to egg shaped. Erect. Green or purplish. Alternate and held close to the stalk. 2.2-3.5 mm long x 1 mm wide.
Florets - The bisexual one is oval to oblong, rounded top, shorter than spikelet.
Glumes - Upper one, oval to egg shaped, 2-4 ribs near the edges, middle is papery.
Palea - The bisexual one is hard, thin and brittle.
Lemma - Empty one similar to the glume. Bisexual one is hard, thin and brittle.
Stamens -
Anthers -

Seeds:

2.2-3.5 mm long x 1 mm wide.

Roots:

Creeping stems that root at the nodes. Fibrous underground roots. Occasionally forms rhizomes.

Key Characters:

No auricles.
Short membranous ligule.
Flattened, keeled, striped, deeply split sheath with translucent edges.
Adapted from J.H. Moore.

Biology:

Life cycle:

Perennial.

Physiology:

Reproduction:

Flowering times:

October to March.

Seed Biology and Germination:

Vegetative Propagules:

Stem fragments.

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Spreads by creeping stems that root at the nodes.

Origin and History:

Tropical America.
Introduced as a lawn grass.

Distribution:

NSW, QLD, WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Warm moist areas. Intolerant of drought.

Climate:

Soil:

Plant Associations:

Significance:

Beneficial:

Lawn grass
Spring and early summer fodder grass.

Detrimental:

Weed of other lawns, poor pastures, rotation crops, disturbed areas and grassland.

Toxicity:

None reported.

Legislation:

None.

Management and Control:

Thresholds:

Eradication strategies:

Herbicide resistance:

Biological Control:

Related plants:

Narrow leaved Carpet grass (A. affinis).

Plants of similar appearance:

Narrow leaved Carpet grass (Axonopus affinis) has longer, narrower leaves and longer flowering heads and no hairs on the leaves. The fertile lemma is 0.8 x the length of the spikelet whilst in Axonopus compressus it is the same length.
Summer grass (Digitaria sanguinalis) has hairy leaves that distinguish it from Carpet grass.

References:

Ciba Geigy (1980) Grass Weeds 1. CIBA GEIGY Ltd, Basle, Switzerland. P10. Diagrams.

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #153.2.

Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). p942.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.