Sehima Fl. Aegypt.-Arab.178 (1775).
Derivation:. From the Eyptian vernacular name of the type, fide H.T.Clifford, Etymological Dictionary of Grasses (1996). Named after the Arab sign Saehim, fide S.D.J.E.Senaratna, The Grasses of Ceylon (1956).
Key references (keys and floras):. C.A.Gardner, Flora of Western Australia 1 Gramineae 301 (1952); J.W.Vickery, Flora of New South Wales, Gramineae 19: 21–22 (1961); E.E.Henty, Manual Grasses New Guinea 170 (1969); M.Lazarides, Tropical Grasses S.E. Asia 71 (1980); J.C.Tothill and J.B.Hacker, Grasses of Southern Queensland 372–373 (1983); B.K.Simon, Flora of the Kimberley Region 1216 (1992); B.K.Simon, Key to Australian Grasses 155(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, 366–367 (2008).
W.D.Clayton & S.A.Renvoize, Genera Graminum (1986), genus (603).
Native. 5 species, from Old World Tropics. 1 species in Australia, WA, NT, Qld, and NSW. Also New Guinea.
Habit. Annual or perennial, tufted. Leaf blades narrow. Ligule a fringed membrane or a fringe of hairs.
Inflorescence. Inflorescence a single raceme (a single, curved, culm-like raceme with embedded spikelets), a single raceme or spike. Spikelet-bearing axes spikelike (laterally compressed, curved), with heteromorphic spikelets, solitary, with spikelets in pairs, one sessile, the other pedicelled, disarticulating at joints. Internodes densely long-hairy (with white hairs ventrally).
Spikelets. Spikelets all partially embedded in rachis, 2 flowered, with 1 fertile floret, paired, sessile and pedicelled, in pedicelled/sessile combinations; sessile spikelet with lower incomplete floret. Fertile spikelets slightly dorsally compressed or laterally compressed and dorsally compressed (commonly more or less square in section), falling with glumes.
Glumes. Glumes more or less equal, long relative to adjacent lemmas, without conspicuous tufts or rows of hairs, awned (the upper with an apical bristle-like awn, the lower bidentate or 2-mucronate), dissimilar (the lower 2-keeled and 2-winged, the upper naviculate-subulate and awned). Lower glume two-keeled (scarcely winged), concave on back or sulcate on back, relatively smooth, 3–6 nerved. Upper glume 3–6 nerved.
Florets. Lower incomplete floret(s) male. Lemmas awnless, similar in texture to fertile lemmas (hyaline), not becoming indurated. Fertile florets 1. Lemmas less firm than glumes (hyaline), not becoming indurated, incised, awned, 2–3 nerved, hairy (above) or glabrous. Awns 1, from a sinus, geniculate, hairless to hairy (puberulous to ciliate along its coils), much longer than body of lemma. Palea relatively long, 2 nerved. Lodicules 2. Stamens 3. Grain concave on one side, compressed dorsiventrally. Hilum short. Embryo large. Pedicels free of rachis. Pedicelled spikelets present, similar in shape to sessile spikelet, male.
Kranz Anatomy. C4.
2n = 34 and 40.
Habitat. Helophytic to mesophytic. Savanna, sometimes on heavy clay. Species of open habitats.
Classification. Panicoideae; Andropogoneae.
Notes. Although variable in certain key characters, the genus is remarkably uniform in general facies, the shape and nervation of the pedicelled spikelet being particularly characteristic. It can be regarded as a segregate from Ischaemum (Clayton and Renvoize, 1986).
Types Species. S. ischaemoides Forssk.
Biogeographic Element. Clifford & Simon 1981, Simon & Jacobs 1990: Old World Tropics.