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Heteropogon

Heteropogon Syn. Pl. 2: 533 (1807).

Derivation:. From Greek heteros (different) and pogon (beard), alluding to the difference between the awnless male and awned female spikelets.

Taxonomic revisions, nomenclatural references:. N.L.Bor, Grasses of Burma, Ceylon, India and Pakistan (excluding Bambuseae) 162–166 (1960).

Key references (keys and floras):. G.Bentham, Flora Australiensis 7: 516–517 (1878); C.A.Gardner, Flora of Western Australia 1 Gramineae 341 (1952); J.W.Vickery, Flora of New South Wales, Gramineae 19: 57–58 (1961); E.E.Henty, Manual Grasses New Guinea 108 (1969); M.Lazarides, Tropical Grasses S.E.Asia 46–47 (1980); M.Lazarides, Flora of Central Australia 494 (1981); J.C.Tothill and J.B.Hacker, Grasses of Southern Queensland 258–260 (1983); B.K.Simon, Flora of the Kimberley Region 1177, 1179 (1992); B.K.Simon, Key to Australian Grasses 123 (1993); S.W.L.Jacobs and C.A.Wall, Flora of New South Wales 4: 446 (1993); D.Sharp and B.K.Simon, AusGrass (2002); S.W.L.Jacobs, R.D.B.Whalley & D.J.B.Wheeler, Grasses of New South Wales, 4th ed, 272–273 (2008).

W.D.Clayton & S.A.Renvoize, Genera Graminum (1986), genus (621).

Native. 7 species, from tropical regions. 2 species in Australia, WA, NT, SA, Qld, and NSW. Also New Guinea and Malesia.

Habit. Annual or perennial, tufted. Leaf blades narrow. Ligule a fringed membrane.

Inflorescence. Inflorescence a single raceme or paniculate (the single racemes sometimes in false panicles), a single raceme or spike, spatheate or espatheate, a compound pseudo-inflorescence (when having axillary fascicles) or not a compound pseudo-inflorescence. Spikelet-bearing axes racemes (of several to many joints), with heteromorphic spikelets, solitary, with spikelets in pairs, one sessile, the other pedicelled, disarticulating at joints (between the heterogamous upper spikelet pairs). Internodes disarticulating obliquely.

Spikelets. Spikelets subterete to dorsally compressed (subterete), 2 flowered, with 1 fertile floret, paired, in pedicelled/sessile combinations (but the pedicel reduced to a short stump, the spikelet being supported on a long, slender callus); sessile spikelet with lower incomplete floret. Fertile spikelets falling with glumes.

Glumes. Glumes more or less equal, long relative to adjacent lemmas, hairy, awnless, dissimilar (the upper with deep longitudinal grooves). Lower glume convex on back, relatively smooth or tuberculate, 5–9 nerved. Upper glume 3 nerved.

Florets. Lower incomplete floret(s) sterile. Lemmas awnless, 0 nerved, similar in texture to fertile lemmas (hyaline), not becoming indurated. Fertile florets 1. Lemmas stipitate-cartilaginous below, produced into the awn, less firm than glumes (hyaline), not becoming indurated, entire at apex, awned, 3 nerved. Awns 1, apical, geniculate, hairy, much longer than body of lemma. Palea present or absent, when present, very reduced, nerveless. Callus long, pointed. Lodicules when present, 2. Stamens 0–3. Grain longitudinally grooved (channelled on one side), compressed dorsiventrally. Hilum short. Embryo large. Pedicels free of rachis. Pedicelled spikelets present, similar in shape to sessile spikelet, sterile or male, with glumes.

Kranz Anatomy. C4.

2n = 20, 22, 40, 44, 50, 60, and 80, 2, 4, 6, and 8 ploid.

Habitat. Mesophytic to xerophytic. Dry places, often on poor soils. Species of open habitats.

Classification. Panicoideae; Andropogoneae.

Types Species. H. glaber Pers. = H. contortus (L.) Roemer & Schultes.

Biogeographic Element. Clifford & Simon 1981, Simon & Jacobs 1990: Gondwanan.

AVH 2011

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith