Ischaemum Sp.Pl. 1049 (1753).
Derivation:. From Greek ischo (to restrain) and haima (blood), alluding to the property of the woolly seeds of the type species to be able to control bleeding.
Syn: Digastrium (Hack.) A.Camus.
Taxonomic revisions, nomenclatural references:. C.E.Hubbard, Hookers Icones Plantarum 33. t.3263: 1–4 (1935); B.K. Simon, Austrobaileya 3: 86–89 (1989).
Key references (keys and floras):. G.Bentham, Flora Australiensis 7: 518–522 (1878); C.A.Gardner, Flora of Western Australia 1 Gramineae 298–301 (1952); J.W.Vickery, Flora of New South Wales, Gramineae 19: 19–21 (1961); E.E.Henty, Manual Grasses New Guinea 72 (1969) as Digastrium and 115–117; M.Lazarides, Tropical Grasses S.E. Asia 50–53 (1980); J.C.Tothill and J.B.Hacker, Grasses of Southern Queensland 282–284 (1983); B.K.Simon, Flora of the Kimberley Region 1181 (1992); B.K.Simon, Key to Australian Grasses 126 (1993); S.W.L.Jacobs and C.A.Wall, Flora of New South Wales 4: 429–430 (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, 284–286 (2008).
W.D.Clayton & S.A.Renvoize, Genera Graminum (1986), genus (597).
Native. 60 species, from tropical and subtropical regions. 11 species in Australia, WA, NT, Qld, and NSW. Also New Guinea and Malesia.
Habit. Annual or perennial, rhizomatous or stoloniferous or tufted or decumbent. Leaf blades broad (rarely) or narrow, cordate or not cordate. Ligule an unfringed membrane.
Inflorescence. Inflorescence terminal or axillary, of spicate main branches, a single raceme or spike or of digitate or subdigitate racemes or spikes, usually digitate, spatheate (the uppermost leaf reduced to a spatheate sheath) or espatheate. Spikelet-bearing axes racemes, with heteromorphic spikelets (the pedicelled spikelet sometimes much smaller, often asymmetric) or with homomorphic spikelets, paired or clustered (rarely solitary), with spikelets in pairs, one sessile, the other pedicelled, disarticulating at joints. Internodes glabrous, or more often hairy.
Spikelets. Spikelets dorsally compressed, 2 flowered, with 1 fertile floret, paired, in pedicelled/sessile combinations or unequally pedicelled in each combination; sessile spikelet with lower incomplete floret. Fertile spikelets falling with glumes.
Glumes. Glumes more or less equal, long relative to adjacent lemmas, awned (the upper, sometimes) or awnless, dissimilar (the lower leathery and usually 2-keeled, the upper 1-keeled above and sometimes awned). Lower glume usually two-keeled (winged or not), convex on back to concave on back, relatively smooth (rarely) or rugose (transversely) or tuberculate (on the margins), 7–11 nerved. Upper glume 5–11 nerved.
Florets. Lower incomplete floret(s) male. Lemmas awnless, similar in texture to fertile lemmas, not becoming indurated. Fertile florets 1. Lemmas less firm than glumes (firmly membranous), not becoming indurated, incised, awned (usually) or mucronate or muticous (rarely), without a germination flap, 1–5 nerved, glabrous. Awns when present 1, or mucros from a sinus, geniculate, hairless (glabrous), much shorter than body of lemma to much longer than body of lemma. Palea relatively long, apically notched, thinner than lemma (hyaline), nerveless. Lodicules 2. Stamens 3. Grain compressed dorsiventrally or terete. Hilum short. Embryo large. Pedicels free of rachis (usually stoutly linear to obovoid, sometimes very short). Pedicelled spikelets present, similar in shape to sessile spikelet or different from sessile spikelet, male.
Kranz Anatomy. C4.
2n = 18, 20, 40, 54, 56, and 68, 2, 4, 6, and 8 ploid (?), commonly adventive.
Habitat. Helophytic (mostly), mesophytic, xerophytic. Some in damp or shady places, some (e.g. I. muticum, I. triticeum) in coastal sand. Shade species, or species of open habitats.
Classification. Panicoideae; Andropogoneae.
Types Species. I. muticum L.
Biogeographic Element. Clifford & Simon 1981, Simon & Jacobs 1990: Gondwanan.