Triodia rigidissima (Pilg.) M. Lazarides. Austral. Syst. Bot. 10: 468 (1997).
Classification. (GPWG 2001) : Subfamily Chloridoideae. Triodeae.
Basionym and/or
Replacement Name: Triraphis
rigidissima Pilg.,.
Type of Basionym or
Protologue Information: Western Australia: Eremaean Province; 25 km from
Menzies, 28 Oct 1901, L. Diels 5175 (HT: B; IT: K).
Recent synonyms:
Plectrachne rigidissima.
Key references
(books and floras): [1952] C.A.Gardner, Flora of Western Australia 1
Gramineae (82 as Plectrachne), [2002] D.Sharp & B.K.Simon, AusGrass,
Grasses of Australia.
Illustrations:
[2005] K.Mallet (ed.), Flora of Australia 44B: Poaceae 3 (Fig.
37I-L).
Habit.
Perennial. Rhizomes absent or present, elongated. Culms erect, 20–70 cm tall.
Mid-culm internodes glabrous. Lateral branches branched. Leaf-sheaths glabrous
on surface. Leaf-sheath auricles absent. Ligule a fringe of hairs. Leaf-blades
spreading, straight, aciculate, conduplicate, 2–8 cm long, 2 mm wide.
Leaf-blade surface glabrous.
Inflorescence.
Inflorescence compound, a panicle. Panicle lanceolate, loose, 7–9 cm long,
(1.5–)4–6 cm wide.
Spikelets.
Spikelets pedicelled. Fertile spikelets many flowered, with at least 2 fertile
florets (4–5), comprising 4–5 fertile floret(s), with diminished florets at the
apex, elliptic, laterally compressed, 9–13 mm long.
Glumes.
Glumes similar. Lower glume lanceolate, scarious or cartilaginous, without
keels, 3–5(–9) -nerved. Lower glume surface glabrous. Lower glume apex muticous
or awned. Upper glume lanceolate, 9–13(–18) mm long, scarious or cartilaginous,
without keels, 3–5(–9) -nerved. Upper glume surface glabrous. Upper glume apex
entire, muticous or awned.
Florets.
Fertile lemma 4–7 mm long, without keel. Lemma surface indumented. Lemma apex
lobed, awned, 3 -awned. Median (principal) awn 11–17 mm long overall. Lateral
lemma awns present. Palea 2 -nerved. Lodicules present. Anthers 3.
Continental
Distribution: Australasia.
Australian
Distribution: Western Australia.
Western Australia:
Canning, Carnarvon, Austin. Coolgardie.
Notes.
Distinguished by the few-nerved entire glumes subequal to the spikelet. Allied
to P. desertorum, but differing by the above characters, as well as its
shorter, fewer flowered spikelets and usually shorter panicle. The sides of the
lemma are usually glabrous and smooth, but occasionally are pubescent or
hirsute in the lower part.
In
the SW Eremaean Province of W.A. In red, yellow and brown, often deep, sands
and loamy sands on hillslopes and sandplains in association with shale,
limestone and laterite; flowers mainly Sept.-Jan., but also Apr. and August.
