Panicum laevinode Lindl. Mitchell,
Three exped. Int. East. Austr. 1: 235 (1838).
Classification. (GPWG 2001) : Subfamily Panicoideae. Paniceae.
Type of Basionym or
Protologue Information: LT: Mitchell's expedition s.n. specimen no. 3,
Australia (CGE (right-hand specimen)). LT designated by Jacobs, Kew Bull.
40(3): 662 (1985).
Key references
(books and floras): [1952] C.A.Gardner, Flora of Western Australia 1
Gramineae (259 as P. Whitei), [1981] M.Lazarides in J.Jessop
(ed)., Flora of Central Australia (471 as P. whitei), [2002]
D.Sharp & B.K.Simon, AusGrass, Grasses of Australia, [2006]
J.Jessop, G.R.M.Dashorst, F.M.James, Grasses of South Australia (462),
[2008] S.W.L.Jacobs, R.D.B.Walley & D.J.B.Wheeler, Grasses of New South
Wales (316).
Illustrations:
[2006] J.Jessop, G.R.M.Dashorst, F.M.James, Grasses of South Australia (463, Fig. 396), [2008] S.W.L.Jacobs,
R.D.B.Whalley & D.J.B.Wheeler, Grasses of New South Wales, 4th edn
(316).
Habit. Annual
or perennial. Rhizomes absent. Stolons absent. Culms erect, 15–120 cm tall,
compressible, 2–7 -noded. Mid-culm internodes glabrous or pilose. Mid-culm
nodes glabrous or pubescent. Lateral branches simple or sparsely branched.
Leaf-sheaths glabrous on surface or hairy. Leaf-sheath auricles absent. Ligule
a fringed membrane, a ciliolate membrane, 1–2 mm long. Leaf-blades linear, 5–20
cm long, 2.5–8 mm wide. Leaf-blade surface smooth, glabrous or indumented.
Inflorescence.
Inflorescence compound, a panicle. Panicle ovate, 5–30 cm long, evenly
furnished or with spikelets clustered towards branch tips.
Spikelets.
Spikelets pedicelled. Fertile spikelets 2-flowered, the lower floret barren
(rarely male), the upper fertile, comprising 1 basal sterile florets,
comprising 1 fertile floret(s), without rachilla extension, elliptic or ovate,
dorsally compressed, 2.3–3.5 mm long. Rhachilla internodes elongated between
glumes.
Glumes. Glumes
thinner than fertile lemma. Lower glume oblate or obovate, membranous, without
keels, 0–5 -nerved. Lower glume apex muticous. Upper glume elliptic, 2.2–3 mm
long, membranous, without keels, 7–9 -nerved. Florets. Basal sterile
florets 1, barren, with palea. Lemma of lower sterile floret 100 % of length of
spikelet, membranous, 7–9 -nerved, muticous.
Fertile lemma 1.7–2.1
mm long, without keel, 7 -nerved. Lemma apex muticous. Anthers 3. Grain 1.5 mm
long.
Continental
Distribution: Australasia.
Australian
Distribution: Western Australia, Northern Territory, South Australia,
Queensland, New South Wales.
Western Australia:
Gardner, Dampier. Canning, Keartland, Fortescue, Ashburton, Carnarvon. Northern
Territory: Darwin & Gulf, Victoria River, Barkly Tableland, Central
Australia North, Central Australia South. South Australia:
North-western, Lake Eyre, Gairdner-Torrens Basin, Flinders Ranges, Eastern,
Murray. Queensland: Burke, Cook, Darling Downs, Gregory North,
Leichhardt, Maranoa, Mitchell, North Kennedy, Port Curtis, South Kennedy,
Warrego, Gregory South. New South Wales: Central-Western Slopes,
South-Western Slopes, North-Western Plains, South-Western Plains, North Far
Western Plains.
Notes.
Morphologically similar to P. decompositum and these taxa are frequently
confused. Diagnostic features of P. laevinode include spikelet length,
presence of a well developed lower palea, and relative size and shape of the
lower glume. Characters which serve to distinguish it from P. decompositum
are the slender drooping primary branches of the inflorescence with spikelets
clustered at the ends of the branches, and the annual or biennial growth habit.
The primary branches of P. decompositum are rigid and distinctly
flattened and swollen at the base.
In Brigalow forests,
tropical and subtropical sub-humid woodlands, semi-arid shrub woodlands, acacia
shrublands, arid tussock grasslands, and arid hummock grasslands. An important
forage species over a wide area of arid and semiarid central Australia. Flowers
throughout the year.
