Digitaria radicosa

Digitaria radicosa (Miq,) Miq. Fl. Ind. Bat. 3: 437 (1855).

Classification. (GPWG 2001) : Subfamily Panicoideae. Paniceae.

Basionym and/or Replacement Name:  Panicum radicosum J. Presl, Reliq. Haenk. 1(4–5): 297 (1830).

Type of Basionym or Protologue Information: Philippine Islands: Luzon: Sorsogon Prov., T. Haenke s.n. (HT: P; IT: US-80950 (fragm.)).

Recent synonyms: D. timorensis.

Key references (books and floras): [2002] D.Sharp & B.K.Simon, AusGrass, Grasses of Australia.

Habit. Annual. Rhizomes absent. Stolons absent. Culms decumbent or sprawling, stature slender to delicate, 20–60 cm tall, 2–5 -noded. Mid-culm internodes glabrous. Mid-culm nodes glabrous. Lateral branches sparsely branched. Leaf-sheaths glabrous on surface. Leaf-sheath auricles present. Ligule an eciliate membrane. Leaf-blades lanceolate, flat, 2–10 cm long, 2–5 mm wide. Leaf-blade surface smooth, glabrous.

Inflorescence. Inflorescence digitate or subdigitate, with racemose branches. Racemes 2–4, 3–9 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, lanceolate, dorsally compressed, 2.5–3.3 mm long. Rhachilla internodes brief up to lowest fertile floret.

Glumes. Glumes dissimilar, thinner than fertile lemma. Lower glume ovate, hyaline, without keels, 0 -nerved. Upper glume lanceolate, 1.1–1.6 mm long, membranous, without keels, 1–3 -nerved. Upper glume surface indumented. Florets. Basal sterile florets 1, barren, without significant palea. Lemma of lower sterile floret 100 % of length of spikelet, membranous, 5–7 -nerved.

Fertile lemma 2.6–3.2 mm long, without keel. Lemma apex muticous. Lodicules present.

Continental Distribution: Africa, Temperate Asia, Tropical Asia, Australasia, and Pacific.

Australian Distribution: Queensland, Christmas Is.

Queensland: Cook.

Notes. Intermediate between D. ciliaris and D. setigera, characterized by the absence of pronounced spicules on the margins of primary branches and a relatively narrow spikelet.

Aso Malesia. In tropical and subtropical rain forests and tropical and subtropical sub-humid woodlands. Common throughout Malesia but is known only from two collections in Australia. Flowers July.

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