Digitaria ischaemum*

Digitaria ischaemum* (Schreb.) Muhl. Descr. Gramin. 131 (1817).

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

Basionym and/or Replacement Name:  Panicum ischaemum Schreb., Spec. Fl. Erlang. 16 (1804).

Type of Basionym or Protologue Information: T: Europe.

Recent synonyms: Panicum glabrum.

Key references (books and floras): [2002] D.Sharp & B.K.Simon, AusGrass, Grasses of Australia, [2006] J.Jessop, G.R.M.Dashorst, F.M.James, Grasses of South Australia (442), [2008] S.W.L.Jacobs, R.D.B.Walley & D.J.B.Wheeler, Grasses of New South Wales (218).

Illustrations: [2006] J.Jessop, G.R.M.Dashorst, F.M.James, Grasses of South Australia  (442, Fig. 373), [2008] S.W.L.Jacobs, R.D.B.Whalley & D.J.B.Wheeler, Grasses of New South Wales, 4th edn (218).

Habit. Annual. Stolons absent. Culms geniculately ascending or decumbent, 10–40 cm tall, 2–4 -noded. Mid-culm internodes glabrous. Mid-culm nodes glabrous. Lateral branches sparsely branched. Leaf-sheaths glabrous on surface. Leaf-sheath auricles absent. Ligule an eciliate membrane, 1–2 mm long. Leaf-blades flat, 1.5–12 cm long, 2–7 mm wide. Leaf-blade surface smooth, glabrous.

Inflorescence. Inflorescence digitate or subdigitate, with racemose branches. Racemes 2–8, 1.5–7 cm long. Central inflorescence axis 0.5–3 cm long.

Spikelets. Spikelets pedicelled, 3 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, dorsally compressed, 1.75–2.5 mm long. Rhachilla internodes brief up to lowest fertile floret.

Glumes. Glumes thinner than fertile lemma. Upper glume elliptic, 1.7–2 mm long, membranous, 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, 7 -nerved.

Fertile lemma 1.7–2.5 mm long, without keel. Lemma apex muticous. Lodicules present. Anthers 3.

Continental Distribution: Europe, Temperate Asia, Tropical Asia, Australasia, North America, and South America.

Australian Distribution: South Australia, New South Wales, Victoria.

South Australia: Murray, Southern Lofty. New South Wales: Central Coast, Central Tablelands, Southern Tablelands, North-Western Slopes, Central-Western Slopes, South-Western Slopes. Victoria: East Gippsland, Gippsland Plain, Wannon.

Notes. Closely related to and easily confused with D. violascens.

Introduced. In tropical and subtropical wet sclerophyll forests, temperate wet sclerophyll forests, dry sclerophyll forests, tropical and subtropical sub-humid woodlands, temperate sub-humid woodlands, semi-arid shrub woodlands, acacia shrublands, and temperate sub-humid grasslands. Commonly occurs in disturbed open habitats, and woodland margins, often invading yards and gardens. Flowers Feb.-Apr.

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