Heterachne Hooker's Icon. Pl. Tab. 13: 39 (1877).

Derivation:. From Greek heteros (other) and achne (glume), referring to the different glumes.

Taxonomic revisions, nomenclatural references:. C.E.Hubbard, Hookers Icones Plantarum 33. t.3284: 1–4 (1935).

Key references (keys and floras):. G.Bentham, Flora Australiensis 7: 634–635 (1878); M.Lazarides, F.Quinn and J.Palmer, Flora of the Kimberley Region 1177 (1992); B.K.Simon, Key to Australian Grasses 123 (1993); D.Sharp and B.K.Simon, AusGrass (2002); K.Mallet (ed.), Flora of Australia 44B: Poaceae 3: 412–414 (2005).

W.D.Clayton & S.A.Renvoize, Genera Graminum (1986), genus (364).

Native, endemic. 3 species, from northern Australia. WA, NT, and Qld.

Habit. Annual, tufted. Leaf blades narrow. Ligule a fringed membrane (very reduced) or a fringe of hairs.

Inflorescence. Inflorescence a false spike, with spikelets on contracted axes (several globular heads in an interrupted spike) or paniculate (with sessile heads of spikelets in the upper leaf sheaths), a spike-like panicle, contracted. Spikelet-bearing axes much reduced (to globular heads).

Spikelets. Spikelets more than 2 flowered, with 1 fertile floret or with 2 or more fertile florets, solitary; with naked rachilla extension (and the prolongation sharply bent). Fertile spikelets sub-orbicular or oblong, very much laterally compressed, disarticulating above glumes (these deciduous).

Glumes. Glumes relatively large, unequal to more or less equal, shorter than spikelet, shorter than adjacent lemmas, hairless, glabrous, pointed, awnless, keeled, similar (very compressed-complicate). Lower glume 1 nerved. Upper glume 1–3 nerved.

Florets. Fertile florets 1(–2). Lemmas similar in texture to glumes (membranous), not becoming indurated, entire at apex, blunt, muticous, without a germination flap, 1–3 nerved, glabrous, 1 keeled (winged). Keel winged. Palea relatively long, entire, 2 nerved. Palea keels winged (the wings broad, ciliate). Distal incomplete florets 1–4 (in a fan-shaped cluster), underdeveloped. Lodicules 2. Stamens 3. Grain small, ellipsoid, compressed laterally. Hilum short. Embryo large.

Kranz Anatomy. C4.

Habitat. Mesophytic. In damp depressions.

Classification. Chloridoideae; Cynodonteae.

Notes. Heterachne, Ectrosia and Planichloa form a continuum of variation and their recognition as separate entities requires further investigation (B.K.Simon).

Types Species. H. gulliveri Benth.

Biogeographic Element. Clifford & Simon 1981, Simon & Jacobs 1990: Endemic.

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