Themeda means a depression where water lies after rain and dried up in summer.
Triandra
Other Names
Summary:
A densely tufted, leafy perennial grass to 1 m tall with sharply keeled leaves and large spikelets. Often blue green when actively growing and reddish at maturity
Description:
Cotyledons:
One.
First leaves:
Long and narrow.
Leaves:
Emerging leaf folded. Blade - Long and narrow, 150-500 mm long by 2-5 mm wide, erect, rather stiff, keeled, flat or vee shaped, prominent mid vein. Tip pointed. Rough sharp edges. May be hairs on the margins. Variable hairiness. Ligule - Very short ring of hairs or short and broad with a rounded, flat or notched tip. Auricles - None. Sheath - Flattened, keeled, tubular, thin, papery, coarsely striped, edges translucent. Hairless.
Stems:
Densely tufted, 300-1500 mm tall, erect, stiff, simple or branched, 2-6 nodes and often powdery near the nodes. Hairy or hairless. Nodes hairless.
Flower head:
Loose, interrupted, often drooping, complex panicle, 100-250 mm long with 12-15 mm long racemes of spikelets.
Erectly branched from the sheath with 2 or more clusters of spikelets partially enclosed by a pair of leaves(spathes) that are papery, narrowly egg shaped, 15-60 mm long, keeled, striped with a pointed tip and green becoming brown at maturity. Branches fine and hairless. Lower branches in the axils of culm leaves, upper ones in the axils of leafy bracts.
Breaks below the fertile spikelet leaving the 4 sterile ones.
Triangular clusters of awned spikelets comprising of 4 male or sterile stalkless spikelets, 8-15 mm long that form a cluster around a single fertile stalkless spikelet which is topped by 1-2 stalked male or sterile spikelets.
Flowers:
Spikelets - . Several sterile spikelets and 1 fertile one. Turns dark brown as it ripens. Sharp base with soft brown hairs.
Fertile central spikelets, bisexual, 2-3 mm long, circular in cross section, often very sharp at the base, densely bearded.
Glumes - Lower one 5-10 mm long, 7 ribbed, tightly in rolled. not keeled, shiny and hairless on the lower two thirds and hairy on the upper third. Upper glume with a deep lengthwise groove on each side, hairless or rough. Smooth, glossy on fertile florets. Pale brown, papery, persistent on sterile florets.
Palea - Small or absent
Lemma - Lower one shorter than glumes, empty, narrowly egg shaped, translucent, membranous, hairless, awned or awnless. Upper one with a 50-70 mm long, twisted, hairy, brown and usually once or twice bent awn that breaks easily Stamens - Anthers -
Sterile upper spikelets on hairless stalks and lower ones stalkless but otherwise similar, narrowly egg shaped, 10 mm long, pointed tip, flattened on the back, awnless and becoming brown with age.
Glumes - Lower glume, papery, 9-11 ribbed, pointed tip, keeled near narrowly membranous edges, hairless or with a few tubercle based hairs.
Upper glume slightly shorter than lower one, narrowly egg shaped, translucent, 2 keeled pointed tip, hairy.
Lemma - 6-7 mm long, translucent, obtuse tip, 1 ribbed, 2 keeled upwards with in rolled edges
Seeds:
Dark brown, shiny. Sharp base. Collar of hairs. Long bent awn.
Roots:
Fibrous.
Key Characters:
Inflorescence a raceme, each raceme subtended by a spathe.
Inflorescence glabrous or minutely scabrous.
Rachis of inflorescent not hollowed on either face.
Triplet disarticulating below the callus leaving 4 sterile spikelets.
Fertile spikelet with an involucre of male or sterile spikelets.
Fertile spikelet glabrous except at the summit
Spikelets in triplets (1 bisexual spikelet in each) surrounded by 4 sterile spikelets.
Spikelets in clusters each of which consists of 4 sessile empty spikelets with a triplet between them; each cluster and cluster of clusters subtended by dry or leafy bracts.
Spikelets 2 flowered with upper floret unisexual or bisexual and lower floret male or empty. Falling entire at maturity, disarticulating below the glumes.
Spikelets dorsally compressed.
Glumes firm in texture, stiffer than the membranous lemmas, as long as spikelets and enclosing florets.
Lemmas of fertile spikelets with slender, twisted awns
Lemmas as long as or shorter than the glumes.
Palea present.
Adapted from John Black, Nancy Burbidge and T.D. Macfarlane
Biology:
Life cycle:
Perennial. Seeds germinate in spring to summer.
Physiology:
Reproduction:
By seed.
Flowering times:
July to December and occasionally in May in WA.
Mainly in spring and summer in western NSW.
Throughout the year in SA.
Seed Biology and Germination:
Vegetative Propagules:
Hybrids:
A variable species many hybrids or chromosome races.
Population Dynamics and Dispersal:
Spread by seed.
Origin and History:
Australian native probably or introduced varieties.
Distribution:
ACT, NSW, QLD, NT, SA, TAS, VIC, WA.
Habitats:
Climate:
Wide range from the arid inland to the mountains.
Temperate.
Soil:
Associated with rocky outcrops.
Red or red brown soils.
Drainage lines.
Plant Associations:
Cypress Pine, Bimble Box, Yellow Box and Grey Box
Significance:
Beneficial:
Young growth is grazed.
Detrimental:
Generally little forage value.
Weed of disturbed areas, roadsides and railway lines.
Toxicity:
Not recorded as toxic.
Symptoms:
Treatment:
Legislation:
None.
Management and Control:
It usually drops to low levels when grazed continuously.
In degraded bushland areas spray with 750 mL/ha glyphosate(450g/L) to suppress Kangaroo Grass and allow other natives to establish to restore a more natural balance.
Thresholds:
Eradication strategies:
Spray with 1 litre of glyphosate(450g/L) in 100 L water twice a year until no more seedlings appear.
Plant more desirable perennial grass species.
Herbicide resistance:
None reported.
Biological Control:
Related plants:
Grader Grass (Themeda quadrivalvis)
Tall Oatgrass (Themeda avenacea) is very similar, taller and tends to flower in autumn.
Plants of similar appearance:
Barbed-wire Grass (Cymbopogon refractus) has aromatic leaves, smaller spikelets and tubercle based hairs on the sterile spikelet.
References:
Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P249. Diagram.
Bodkin, F. (1986). Encyclopaedia Botanica. (Angus and Robertson, Australia).
Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P70. Diagram.
Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P147-148. Photo.
Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney).
Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).
Marchant et al (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P995.
Moerkerk, M.R. and Barnett A.G. (1998) More Crop Weeds. (R.G and F.J. Richardson, Melbourne). P44. Photos. Diagrams.
Paterson, J.G. (1977). Grasses in South Western Australia. (Western Australian Department of Agriculture Bulletin 4007). P99. Diagram.
Acknowledgments:
Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.