Coix Sp. Pl. 972 (1753).
Derivation:. From Greek koix, name of a palm (Hyphaena coriacea Gartn.) in the works of Theophrastus as the false "fruits" resemble the fruits of this palm.
Taxonomic revisions, nomenclatural references:. B.K.Simon, Austrobaileya 3: 1–5 (1989).
Key references (keys and floras):. E.E.Henty, Manual Grasses New Guinea 53 (1969); M.Lazarides, Tropical Grasses S.E. Asia 95–96 (1980); J.C.Tothill and J.B.Hacker, Grasses of Southern Queensland 168–169 (1983); B.K.Simon, Key to Australian Grasses 86 (1993); S.W.L.Jacobs and C.A.Wall, Flora of New South Wales 4: 427–428 (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, 188 (2008).
W.D.Clayton & S.A.Renvoize, Genera Graminum (1986), genus (651).
Native and naturalised. 5 species, from tropical Asia and Australia. 3 species in Australia, WA, Qld, and NSW. Also New Guinea and Malesia.
Habit. Annual to perennial, rhizomatous and single-stemmed (stems erect or straggling, with prop-roots from the lower nodes). Leaf blades broad, cordate or not cordate. Ligule an unfringed membrane to a fringed membrane. Plants monoecious with all fertile spikelets unisexual, male and female-fertile spikelets on different branches of same inflorescence (in different but apposed, spiciform racemes within the pistillate sheath).
Inflorescence. Inflorescence paniculate (but peculiar), a spatheathe panicle, spatheate, racemes single, not in tight heads, a compound pseudo-inflorescence (the partial inflorescences of peculiar form, on flattened peduncles, in leafy panicles). Spikelet-bearing axes much reduced (the female raceme usually represented by three spikelets, enclosed in a globose, hardened involucre, the male raceme exserted on a peduncle through the apex of the involucre), with heteromorphic spikelets, falling entire.
Spikelets. Spikelets 2 flowered, with 1 fertile floret, sessile and pedicelled, in pedicelled/sessile combinations (in both male and female racemes); sessile spikelet with lower incomplete floret. Fertile spikelets falling with glumes.
Glumes. Glumes more or less equal, long relative to adjacent lemmas, pointed, awnless, dissimilar (both beaked; the lower subglobose, hyaline below, subcartilaginous above; the upper narrower, strongly keeled, subhyaline). Lower glume flattened on back, relatively smooth, many nerved. Upper glume 11 nerved.
Florets. Lower incomplete floret(s) sterile. Lemmas awnless, 3–7 nerved, decidedly firmer than fertile lemmas, not becoming indurated. Fertile florets 1. Lemmas deltoid, less firm than glumes to similar in texture to glumes (similar to the upper glume, but less strongly keeled; very thin and hyaline beneath the beak), not becoming indurated, entire at apex, pointed, mucronate (beaked), 3–5 nerved, glabrous, 1 keeled (but less conspicuously so than the upper glume). Palea conspicuous and relatively short (broad, beaked), entire (subulate-beaked), 2 nerved. Stamens 0 (or 3 staminodes). Grain medium sized, compressed dorsiventrally. Hilum short (circular or elliptical, quite large). Embryo large. Pedicels free of rachis. Pedicelled spikelets with glumes, with proximal incomplete florets or without proximal incomplete florets (the lower floret sterile or male), 2 floreted.
Kranz Anatomy. C4.
2n = 10, 20, and 40, 2, 4, and 8 ploid, commonly adventive.
Habitat. Helophytic to mesophytic. Forest margins and swamps. Shade species, or species of open habitats.
Classification. Panicoideae; Andropogoneae.
Notes. An extraordinary modification in which protection of the disseminule is provided by a hard flask-like spatheole. The presence of a prophyll between male and female racemes indicates that this is a compound structure derived from the union of two separate inflorescences (Clayton & Renvoize, 1986).
Types Species. C. lacryma-jobi L.
Biogeographic Element. Clifford & Simon 1981, Simon & Jacobs 1990: Old World Tropics.