Queensland Blue Couch

Digitaria didactyla Willd.

Order: Poales

Family: Poaceae

Names:

Digitaria
Didactyla
Queensland Blue Couch.

Other Names

Queensland Blue.

Summary:

A soft and fine leaved, perennial, stoloniferous turf grass.

Description:

Cotyledons:

One.

Leaves:

Blade - Parallel sided, fine, soft, in folded, 40-120 mm long x 1-2 mm wide. Hairless or with a few scattered hairs.
Ligule - Flat topped, 1 mm long.
Auricles -
Sheath - Striped.

Stems:

Low lying, creeping, stolons up to 2000 mm long and 100-700 mm tall. Forms roots at the nodes.
Flower stem - Many nodes with short internodes. Nodes hairy.

Flower head:

2-4 finger like stalkless racemes 40-50 mm long carried on a stalk(peduncle) that sticks out from the sheath by 50-150 mm. Main axis(rachis) curved, angular and smooth on the edges.

Flowers:

Spikelets - 2-3 mm long, in pairs, loosely overlapping, on different length stalks(pedicels)
Florets -
Glumes - Lower one tiny, less than 0.5 mm long, rounded. Upper one 1.5-2 mm long, 3-5 ribbed, fine white hairs on the edges and sometimes on the surface.
Palea - Almost the same length as the lemma, pointed tip.
Lemma - Lower one 2-3 mm long, 5-7 ribbed, and rough between the ribs and on the edges. Upper lemma almost the same length as the lower lemma, narrowly egg shaped, smooth, pointed tip.
Stamens -
Anthers -

Fruit:

Seeds:

Roots:

Fibrous.

Key Characters:

Ligule is flat topped and 1 mm long.
Sheath - Striped.

Creeping stolons.
Turf grass.

Biology:

Life cycle:

Perennial.

Physiology:

Reproduction:

Flowering times:

January to March in Perth.
Summer in WA.

Seed Biology and Germination:

Vegetative Propagules:

Stolon fragments.

Hybrids:

Population Dynamics and Dispersal:

Spread mainly by intentional planting and escapes from garden situations.

Origin and History:

Canary Islands. Tropical areas.

Distribution:

NSW, QLD, WA.
Naturalised in WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Temperate. Sub tropical.

Soil:

Prefers moist sandy soils.

Plant Associations:

Significance:

Beneficial:

Lawn grass.

Detrimental:

Weed of swamps and disturbed areas.

Toxicity:

Not recorded as toxic.

Legislation:

None.

Management and Control:

Thresholds:

Eradication strategies:

Apply glyphosate in autumn and spring to actively growing grass.

Herbicide resistance:

Biological Control:

Related plants:

Cotton Panic grass (Digitaria brownii)
Crabgrass (Digitaria sanguinalis)
Curly Umbrella grass (Digitaria hystrichoides)
Finger Panic grass (Digitaria coenicola)
Queensland Blue Couch (Digitaria didactyla)
Silky Umbrella grass (Digitaria ammophila)
Small Flowered Finger grass (Digitaria parviflora)
Smooth Summer grass (Digitaria ischaemum)
Summer Grass (Digitaria ciliaris)
Tufted Umbrella grass (Digitaria hubbardii)
Umbrella grass (Digitaria divaricatissima)
Woolly Finger grass (Digitaria eriantha)

Plants of similar appearance:

Blue Couch Grass (Cynodon incompletus)
Couch Grass (Cynodon dactylon)
English Couch (Elytrigia repens)

References:

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P51.

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #437.6.

Marchant et al (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P955.

Acknowledgments:

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