Psammagrostis Hooker's Icon. Pl. 34: t. 3361 (1938).
Derivation:. From the Greek psammos (sand) and agrostis (a kind of grass).
Key references (keys and floras):. C.A.Gardner, Flora of Western Australia 1 Gramineae 111–113 (1952); B.K.Simon, Key to Australian Grasses 152 (1993); D.Sharp and B.K.Simon, AusGrass (2002); K.Mallet (ed.), Flora of Australia 44B: Poaceae 3: 411–412 (2005).
W.D.Clayton & S.A.Renvoize, Genera Graminum (1986), genus (360).
Native, endemic. 1 species. WA.
Habit. Annual, decumbent (to geniculate ascending). Leaf blades narrow. Ligule a fringe of hairs.
Inflorescence. Inflorescence falsely paniculate (towards the culm tips, by proliferation of the axillary fascicles which occur in simpler form with the lower leaves), a compound pseudo-inflorescence. Spikelet-bearing axes much reduced (each to a deciduous, slightly clavate, 3–10 mm peduncle, with a terminal spikelet and often with one or two sessile, subsessile or more or less pedicellate lateral spikelets), clustered (2–4 per axil), falling entire (the striated peduncles disarticulating at the base).
Spikelets. Spikelets somewhat laterally compressed, sessile, subsessile, and pedicelled; with naked rachilla extension. Fertile spikelets somewhat laterally compressed, falling with glumes (and with their companions on the peduncle), with distinctly elongated rachilla internodes between florets (up to 2 mm long, clavate).
Glumes. Glumes unequal, shorter than spikelet, hairless, slightly scabrous, blunt (erose), awnless, keeled, dissimilar to similar (the lower flimsier, sometimes hyaline throughout). Lower glume 0 nerved or 1 nerved. Upper glume 3–5 nerved (female spikelet).
Florets. Fertile florets 3–7. Lemmas elliptical to broadly ovate, decidedly firmer than glumes (leathery or cartilaginous, with hyaline margins), entire at apex to incised (obtuse, truncate or slightly emarginate), mucronate, without a germination flap, 3 nerved, with nerves non-confluent, 1 keeled. Palea relatively long, tightly clasped by lemma, entire (the hyaline apex rounded), textured like lemma (leathery to cartilaginous between the keels), 2 nerved, 2 keeled. Palea keels wingless, scabrous. Distal incomplete florets underdeveloped. Lodicules 2. Stamens 3. Stigmas 2. Grain small, linear or ellipsoid, trigonous, sculptured. Hilum short. Embryo large.
Kranz Anatomy. C4.
Habitat. Xerophytic. Sandhills. Species of open habitats.
Classification. Chloridoideae; Cynodonteae.
Notes. An unusual genus without obvious relatives, though the spikelets bear some resemblance to Eragrostis dielsii. The peculiar disseminule imitates that of Thaumastochloa (Clayton and Renvoize, 1986).
Types Species. P. wiseana C.A.Gardner & C.E.Hubb.
Biogeographic Element. Clifford & Simon 1981, Simon & Jacobs 1990: Endemic.