Zygochloa Pap. Biol. Univ. Queensland 1(19): 7 (1941).
Derivation:. From Greek zygos (yoke) and chloe (grass), referring to the styles being joined at their bases.
Key references (keys and floras):. J.W.Vickery, Flora of New South Wales, Gramineae No. 19: 267–269 (1975); M.Lazarides, Flora of Central Australia 483 (1981); J.C.Tothill and J.B.Hacker, Grasses of Southern Queensland 440–441 (1983); J.P.Jessop, Flora of South Australia 4: 1980–1981 (1986); R.D.Webster, Australian Paniceae 270–271 (1987); B.K.Simon, Key to Australian Grasses 177 (1993); S.W.L.Jacobs and S.M.Hastings, Flora of New South Wales 4: 504 (1993); D.Sharp and B.K.Simon, AusGrass (2002); J.P.Jessop, Grasses of South Australia 497 (2006); S.W.L.Jacobs, R.D.B.Whalley & D.J.B.Wheeler, Grasses of New South Wales, 4th ed, 403 (2008).
W.D.Clayton & S.A.Renvoize, Genera Graminum (1986), genus (544).
Native, endemic. 1 species, from arid mainland Australia. NT, SA, Qld, and NSW.
Habit. Shrubby perennial, rhizomatous (and tussock-forming). Culms woody and persistent. Leaf blades broad to narrow. Ligule a fringe of hairs. Plants dioecious.
Inflorescence. Inflorescence a spatheate panicle of `bracteate' heads, of two types, open, spatheate (and `bracteate'), a compound pseudo-inflorescence. Spikelet-bearing axes much reduced (to a single spikelet accompanied by two basal bracts and the small, naked, bractlike axis tip, the units grouped into capitate heads), falling entire (the heads falling).
Spikelets. Spikelets dorsally compressed, 2 flowered, with 1 fertile floret, associated with bractiform involucres (each spikelet associated with the three chaffy, rigid-tipped `bracts'), solitary, subsessile. Fertile spikelets with lower incomplete floret(s), lanceolate or ovate, falling with glumes.
Glumes. Glumes more or less equal, shorter than adjacent lemmas, pointed or blunt, awnless, similar (papery). Lower glume 5–9 nerved. Upper glume 5–9 nerved.
Florets. Lower incomplete floret(s) sterile. Lemmas awnless, 5 nerved, becoming indurated. Fertile florets 1. Lemmas abruptly acuminate, decidedly firmer than glumes, smooth or striate, becoming indurated (crustaceous), yellow in fruit, entire at apex, pointed, muticous, 5 nerved, glabrous, having margins tucked into palea. Palea entire (ovate, abruptly acuminate), textured like lemma, 2 nerved. Lodicules 2. Stamens 0 (3 staminodes). Grain small. Hilum short. Pedicelled spikelets with glumes, without proximal incomplete florets, 2 floreted (both fertile).
Kranz Anatomy. C4.
Habitat. Xerophytic. Arid sandy and rocky places. Species of open habitats.
Classification. Panicoideae; Paniceae.
Notes. The papery bracts aid wind dispersal. They are similar in appearance but probably of varied homology; from the lowest upwards they are believed to represent a prophyll, a spatheole and rhachis extension (Clayton and Renvoize, 1986). Phylogenetically Zygochloa is related to Spinifex (Zuolaga, Morrone and Giussani, 2000), both being dioecious, and they are both sister to Xerochloa, which is not dioecious (B.K.Simon).
Types Species. Z. paradoxa (R.Br.) S.T.Blake.
Biogeographic Element. Clifford & Simon 1981, Simon & Jacobs 1990: Endemic.
Zygochloa Pap. Biol. Univ. Queensland 1(19): 7 (1941).
Derivation:. From Greek zygos (yoke) and chloe (grass), referring to the styles being joined at their bases.
Key references (keys and floras):. J.W.Vickery, Flora of New South Wales, Gramineae No. 19: 267–269 (1975); M.Lazarides, Flora of Central Australia 483 (1981); J.C.Tothill and J.B.Hacker, Grasses of Southern Queensland 440–441 (1983); J.P.Jessop, Flora of South Australia 4: 1980–1981 (1986); R.D.Webster, Australian Paniceae 270–271 (1987); B.K.Simon, Key to Australian Grasses 177 (1993); S.W.L.Jacobs and S.M.Hastings, Flora of New South Wales 4: 504 (1993); D.Sharp and B.K.Simon, AusGrass (2002); J.P.Jessop, Grasses of South Australia 497 (2006); S.W.L.Jacobs, R.D.B.Whalley & D.J.B.Wheeler, Grasses of New South Wales, 4th ed, 403 (2008).
W.D.Clayton & S.A.Renvoize, Genera Graminum (1986), genus (544).
Native, endemic. 1 species, from arid mainland Australia. NT, SA, Qld, and NSW.
Habit. Shrubby perennial, rhizomatous (and tussock-forming). Culms woody and persistent. Leaf blades broad to narrow. Ligule a fringe of hairs. Plants dioecious.
Inflorescence. Inflorescence a spatheate panicle of `bracteate' heads, of two types, open, spatheate (and `bracteate'), a compound pseudo-inflorescence. Spikelet-bearing axes much reduced (to a single spikelet accompanied by two basal bracts and the small, naked, bractlike axis tip, the units grouped into capitate heads), falling entire (the heads falling).
Spikelets. Spikelets dorsally compressed, 2 flowered, with 1 fertile floret, associated with bractiform involucres (each spikelet associated with the three chaffy, rigid-tipped `bracts'), solitary, subsessile. Fertile spikelets with lower incomplete floret(s), lanceolate or ovate, falling with glumes.
Glumes. Glumes more or less equal, shorter than adjacent lemmas, pointed or blunt, awnless, similar (papery). Lower glume 5–9 nerved. Upper glume 5–9 nerved.
Florets. Lower incomplete floret(s) sterile. Lemmas awnless, 5 nerved, becoming indurated. Fertile florets 1. Lemmas abruptly acuminate, decidedly firmer than glumes, smooth or striate, becoming indurated (crustaceous), yellow in fruit, entire at apex, pointed, muticous, 5 nerved, glabrous, having margins tucked into palea. Palea entire (ovate, abruptly acuminate), textured like lemma, 2 nerved. Lodicules 2. Stamens 0 (3 staminodes). Grain small. Hilum short. Pedicelled spikelets with glumes, without proximal incomplete florets, 2 floreted (both fertile).
Kranz Anatomy. C4.
Habitat. Xerophytic. Arid sandy and rocky places. Species of open habitats.
Classification. Panicoideae; Paniceae.
Notes. The papery bracts aid wind dispersal. They are similar in appearance but probably of varied homology; from the lowest upwards they are believed to represent a prophyll, a spatheole and rhachis extension (Clayton and Renvoize, 1986). Phylogenetically Zygochloa is related to Spinifex (Zuolaga, Morrone and Giussani, 2000), both being dioecious, and they are both sister to Xerochloa, which is not dioecious (B.K.Simon).
Types Species. Z. paradoxa (R.Br.) S.T.Blake.
Biogeographic Element. Clifford & Simon 1981, Simon & Jacobs 1990: Endemic.