Plinthanthesis Syn. 1: 14 (1853).
Derivation:. From the Greek plinthos (plinth) and anthos (flower), referring to the raceme-like inflorescence.
Key references (keys and floras):. S.W.L.Jacobs and K.L.McClay, Flora of New South Wales 4: 557–558 (1993); N.G.Walsh, Flora of Victoria 2: 524–525 (1994); D.Sharp and B.K.Simon, AusGrass (2002); K.Mallet (ed.), Flora of Australia 44B: Poaceae 3: 30–32 (2005); S.W.L.Jacobs, R.D.B.Whalley & D.J.B.Wheeler, Grasses of New South Wales, 4th ed, 343–344 (2008).
W.D.Clayton & S.A.Renvoize, Genera Graminum (1986), genus (267).
Native, endemic. 3 species, from southeastern Australia. NSW and Vic.
Habit. Perennial, tufted. Leaf blades narrow. Ligule a fringe of hairs.
Inflorescence. Inflorescence paniculate.
Spikelets. Spikelets laterally compressed, pedicelled; with naked rachilla extension. Fertile spikelets laterally compressed, disarticulating above glumes, with distinctly elongated rachilla internodes between florets (the internode more than half the lemma length).
Glumes. Glumes more or less equal, shorter than spikelet to exceeding florets, long relative to adjacent lemmas (exceeding them), hairless, glabrous or scabrous, pointed (acute), awnless, similar (translucent or firm). Lower glume 1 nerved or 3 nerved or 7 nerved. Upper glume 1 nerved or 3 nerved.
Florets. Fertile florets 2–4. Lemmas similar in texture to glumes to decidedly firmer than glumes (firmly membranous to leathery), incised, deeply cleft (to about halfway) or not deeply cleft (the lobes minute, or up to 4 mm long), muticous or mucronate or awned (shortly), without a germination flap, 7 nerved or 9 nerved, not keeled (rounded on the back). Awns when present, 1, from a sinus, geniculate (often bi-geniculate) or non-geniculate (flat or curved), when present, much shorter than body of lemma to about as long as body of lemma. Lemma hairs not in tufts, not in transverse rows (evenly hairy at least in lower half). Palea relatively long (equalling the lemma), entire to apically notched, thinner than lemma to textured like lemma, 2 nerved, 2 keeled. Palea keels wingless. Distal incomplete florets underdeveloped. Callus short, blunt. Lodicules 2. Stamens 3. Stigmas 2. Disseminule a caryopsis enclosed in but free of lemma and palea. Grain small, golden-brown, obovate, longitudinally grooved, compressed dorsiventrally, glabrous. Hilum long-linear. Embryo large. Endosperm hard.
Kranz Anatomy. C3.
Habitat. Mesophytic to xerophytic. Upland heaths. Species of open habitats.
Notes. A member of the Danthonia clade (Danthonia, Notochloë, Plinthanthesis and New Zealand Cortaderia) of the danthonioid grasses (Barker, Morton and Linder, 2000).
Types Species. P. urvillei Steud.
Biogeographic Element. Clifford & Simon 1981, Simon & Jacobs 1990: Endemic.