Panicum decompositum R. Br.
Other names:Australian Millet
Summary:Coarse, densely tufted perennial or occasionally annual grass that forms large tussocks with large leaves and a large open, spreading, fine seed head with shiny, hard seeds. Seed head is often half of the plant.
Leaves:Erect, usually light blue green. Hairless.
Blade - Flat, 5-12 mm wide and up to 500 mm long, tapering to a fine point. Rough whitish edges. Surface hairless. Conspicuous midrib.
Ligule - Very short, 0.5 mm, flat on top. Hairy.
Auricles - None.
Stems: Erect, branched or unbranched, smooth, 300-1450 mm tall, usually thick, soft, hollow. 3-4 conspicuous hairy or hairless nodes. Densely tufted with a hairless of sparsely hairy butt, thickened by several broad, papery, loose and shining bracts.
Flower head:Loose, wide, compound, much branched panicle, 150-400 mm long and wide. Initially enclosed in top leaf sheath, fully exserted and well above the leaves when mature. Lower branches in rings or clustered with a single branch below. Branches and branchlets are stiff, slender, roughened, angular or flattened, wavy or straight. Spikelets are usually in pairs at the ends of branchlets, on unequal stalks, 1-4 mm long.
Flowers: Spikelets - 2.5-3.75 mm long, 2 flowered, pale green or purplish, flattened. Cupped, pointed tips. Hairless.
Florets - Lower one sterile. Upper one fertile, 2-2.2 mm long, smooth, glossy, hard and brittle. Pale then turning yellow to dark brown.
Glumes -outer one membranous and transparent, almost flat on top, one third the length of the spikelet, faintly one nerved. Inner one larger, 7-9 nerved.
Lemma - first one, same length as inner glume, encloses the palea. Second one becomes hard, smooth and shining.
Key Characters:Panicle usually more than 100 mm long and fully exserted when mature. No appendage below the palea. Spikelets to 4 mm long. First glume about half the length of the spikelet with an acute tip. Leaves with at least some hairs. Nodes bearded. Leaf blade 5-12 mm wide.
Perennial or occasionally annual. Flowers throughout the year with a peak in summer and autumn. Produces most growth in summer.
Flowering times:Summer to autumn in western NSW.
All the year in SA.
Seed Biology and Germination:Vegetative Propagules:
Population Dynamics and Dispersal:
Origin and History:Australia.
Distribution:NSW, NT, QLD, SA, VIC, WA.
Courtesy Australia's Virtual Herbarium.
Soil:Heavy clay soils in depressions and gilgais.
Red earths. Duplex soils. Black soils
Flood plain areas.
Dry and moist soils.
Plant Associations:Mitchell grass, black box, bladder saltbush, open grass lands and many other communities.
Good grazing tolerant forage plant. Produces large and reliable quantities of forage after summer rains or flooding.
Palatable but becomes less attractive if left to go rank.
Seed used by aborigines to make flour and cakes.
Detrimental:Weed of roadsides and disturbed areas.
Toxicity:Suspected to be toxic but most cases investigated cast doubt on its toxicity and are usually attributed to associated species causing photo sensitisation.
Management and Control:Thresholds:
Apply glyphosate in autumn and spring.
Herbicide resistance:Biological Control:
Black seeded Panic (Panicum bisulcatum)
Blue Panic (Panicum antidotale)
Bulbous Panic (Panicum bulbosum)
Coolah grass (Panicum coloratum)
Dwarf Panic (Panicum pygmaeum)
Gilgai grass (Panicum subxerophilum)
Green Panic (Panicum maximum var. trichoglume)
Guinea grass (Panicum maximum)
Hairy Panic (Panicum effusum)
Millet Panic (Panicum miliaceum)
Native Panic (Panicum buncei)
Pepper grass (Panicum laevinode)
Rigid Panic (Panicum prolutum)
Swamp Panic (Panicum paludosum)
Sweet Panic (Panicum gilvum)
Torpedo grass (Panicum repens)
Two coloured Panic (Panicum simile)
White Water Panic (Panicum obseptum)
Witchgrass (Panicum capillare)
Yabila grass (Panicum queenslandicum)
Plants of similar appearance:Grasses.
References:Black, J.M. (1978). Flora of South Australia. (Government Printer, Adelaide, South Australia). P221-222. Diagram.
Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P119. Photo.
Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P332.
Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).
Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #926.10.
McBarron, E.J. (1983). Poisonous plants. (Inkata Press, Melbourne). P12-13. Diagram.
Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.