Sorghum Meth. 207 (1794).

Derivation:. The Indian name for this genus.

Taxonomic revisions, nomenclatural references:. B.K.Simon, Qld Journal of Agricultural and Animal Science 36: 71–86 (1979); M.Lazarides, J.B.Hacker and M.H.Andrew, Aust. Syst. Bot. 4: 591–635 (1991); R.E.Spangler, Aust. Syst. Bot. (in press).

Key references (keys and floras):. G.Bentham, Flora Australiensis 7: 539–541 (1878); C.A.Gardner, Flora of Western Australia 1 Gramineae 314–320 (1952); J.W.Vickery, Flora of New South Wales, Gramineae 19: 29–33 (1961); E.E.Henty, Manual Grasses New Guinea 173, 176–177 (1969); M.Lazarides, Tropical Grasses S.E. Asia 72–73 (1980); M.Lazarides, Flora of Central Australia 491 (1981); J.C.Tothill and J.B.Hacker, Grasses of Southern Queensland 378–381(1983); J.P.Jessop, Flora of South Australia 4: 1992–1993 (1986); M.Lazarides, F.Quinn and J.Palmer, Flora of the Kimberley Region 1219–1222 (1992); B.K.Simon, Key to Australian Grasses 155–159 (1993); S.W.L.Jacobs and K.L.McClay, Flora of New South Wales 4: 435–437 (1993); N.G.Walsh, Flora of Victoria 2: 619–620 (1994); E.Edgar and H.E.Connor, Flora of New Zealand 5: 609–611 (2000); D.Sharp and B.K.Simon, AusGrass (2002); J.P.Jessop, Grasses of South Australia 530–533 (2006); S.W.L.Jacobs, R.D.B.Whalley & D.J.B.Wheeler, Grasses of New South Wales, 4th ed, 367–371 (2008).

W.D.Clayton & S.A.Renvoize, Genera Graminum (1986), genus (584).

Native and naturalised. 6 species (species number is variabledepending on the species concept; many cultivated and weedy segregates are recognised at species rank in this treatment), from pantropical and subtropical regions. 6 species in Australia, WA, NT, SA, Qld, NSW, and Vic. Also New Guinea, Malesia and New Zealand.

Habit. Annual or perennial, rhizomatous or stoloniferous or tufted or decumbent. Leaf blades broad or narrow. Ligule an unfringed membrane to a fringed membrane or a fringe of hairs (rarely).

Inflorescence. Inflorescence paniculate or of spicate main branches (usually large, the branched or simple primary branches usually whorled), an open panicle with branches ending in racemes of paired spikelets, open or contracted. Spikelet-bearing axes much reduced or racemes (short racemes with 1–6(-8) articles only), joints with only one spikelet-bearing joint or with 2–3 spikelet-bearing joints or with 4–5 spikelet-bearing joints or with 6–10 spikelet-bearing joints (rarely), with heteromorphic spikelets, falling entire (when reduced to one joint) or disarticulating at joints. Internodes disarticulating transversely.

Spikelets. Spikelets dorsally compressed, 2 flowered, with 1 fertile floret, awned, paired (very rarely in triplets), sessile and pedicelled, in pedicelled/sessile combinations; sessile spikelet with lower incomplete floret. Fertile spikelets falling with glumes or not disarticulating (in cultivated forms).

Glumes. Glumes more or less equal, long relative to adjacent lemmas, awnless or awned (the upper, sometimes), dissimilar (the lower flat or rounded on the back save at the summit, upper naviculate). Lower glume two-keeled (above and winged), convex on back to flattened on back, relatively smooth, 5–11 nerved. Upper glume 3–11 nerved.

Florets. Lower incomplete floret(s) sterile. Lemmas awnless, 0 nerved or 2 nerved, similar in texture to fertile lemmas (hyaline, ciliate), not becoming indurated. Fertile florets 1. Lemmas less firm than glumes (hyaline, ciliate), not becoming indurated, incised, muticous to mucronate (rarely) or awned, 1–3 nerved, glabrous. Awns when present, 1, from a sinus, geniculate, hairless (glabrous), much shorter than body of lemma to much longer than body of lemma. Palea present or absent, when present relatively long or conspicuous and relatively short or very reduced, 2 nerved or nerveless. Callus pointed or blunt. Lodicules 2. Stamens 3. Grain small or medium sized or large, compressed dorsiventrally or terete. Hilum short. Embryo large. Pedicels free of rachis. Pedicelled spikelets present, similar in shape to sessile spikelet, sterile or male.

Kranz Anatomy. C4, biochemical type NADP-ME (3 species).

2n = 10, 20, and 40 (and aneuploids - 26, 33, 38–39 etc.), commonly adventive.

Habitat. Mesophytic. Mainly disturbed ground. Shade species, or species of open habitats.

Classification. Panicoideae; Andropogoneae.

Notes. The taxa of agricultural importance are closely related to S. arundinaceum, and form a complex whose many variants have attracted a deluge of specific names, which have been reduced with greater cytogenetic understanding (Clayton and Renvoize, 1986). The genus has been subdivided into subgenera by Garber (1950), and recent cladistic work by Spangler (in press), based on molecular and morphological data, recognises 3 genera, Sorghum, Sarga and Vacoparis..

Types Species. S. bicolor (L.) Moench.

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