Digitaria nematostachya (F. M. Bailey) Henrard. Monogr. Digitaria 487 (1950).
Classification. (GPWG 2001) : Subfamily Panicoideae. Paniceae.
Basionym and/or Replacement Name: Panicum nematostachyum F.M. Bailey, Queensland Bot. Bull. 16: 2 (1903).
Type of Basionym or Protologue Information: NT: Hubbard & Winders 7668, Australia (CANB; INT: BRI). NT selected by Webster, Brunonia 6: 193 (1983).
Recent synonyms: Digitaria tonsa.
Key references (books and floras): [1810]. R.Brown, Prodromus (192 as Panicum radiatum), [2002] D.Sharp & B.K.Simon, AusGrass, Grasses of Australia.
Habit. Perennial. Rhizomes present, elongated. Stolons absent. Culms erect, 35–55 cm tall, 7–12 -noded. Mid-culm internodes glabrous. Mid-culm nodes glabrous or pubescent. Lateral branches simple. Leaf-sheaths antrorsely scabrous, glabrous on surface or hairy. Leaf-sheath auricles absent. Ligule an eciliate membrane, 1–2.8 mm long, erose, acute. Leaf-blades flat, 6–25 cm long, 3.5–7 mm wide. Leaf-blade surface smooth or scabrous, glabrous or indumented.
Inflorescence. Inflorescence subdigitate, with racemose branches. Racemes 10–20, ascending or spreading, 13–30 cm long, bearing 16–30 fertile spikelets on each. Central inflorescence axis 2.5–11 cm long.
Spikelets. Spikelets pedicelled, 2 in the cluster. Fertile spikelets 2-flowered, the lower floret barren (rarely male), the upper fertile, comprising 1 basal sterile florets, comprising 1 fertile floret(s), without rachilla extension, elliptic or obovate, dorsally compressed, 1.7–2.1 mm long. Rhachilla internodes brief up to lowest fertile floret.
Glumes. Glumes thinner than fertile lemma. Lower glume oblong or ovate, membranous, 0 -nerved. Upper glume ovate, 1.5–1.7 mm long, membranous, without keels, 3 -nerved. Upper glume surface glabrous. Florets. Basal sterile florets 1, barren, without significant palea. Lemma of lower sterile floret 80–90 % of length of spikelet, membranous, 7 -nerved.
Fertile lemma 1.8–2 mm long, without keel. Lemma apex mucronate. Lodicules present.
Continental Distribution: Australasia.
Australian Distribution: Western Australia, Northern Territory, Queensland.
Western Australia: Gardner. Northern Territory: Darwin & Gulf, Victoria River, Barkly Tableland. Queensland: Burke, Cook, North Kennedy, Burnett, Darling Downs.
Notes. A completely glabrous spikelet with the upper lemma protruding past the lower lemma makes D. nematostachya a distinctive member of the Pennatae. Spikelet characteristics of this species are similar to those of the section Parviflorae.
Native; N.T. and Qld. In tropical and subtropical sub-humid woodlands and tropical sub-humid grasslands. Flowers Jan.-Feb.; June-July.
