Common name
Summer Grass
Crab Grass

Derivation
Digitaria Haller, Hist. Stirp. Helv. 2: 244 (1768). From the Latin digitus (finger), alluding to radiating inflorescence branches.

ciliaris- from the Latin cilium (eyelid) and -are (pertaining to). Glumes or lemmas ciliate on nerves or margins.

Published in
Descr. Gram. 27 (1802).

Common synonyms
Digitaria adscendens (Kunth) Henrard

Habit
Annual. Stolons absent. Culms decumbent, 10–100 cm tall, 2–5-noded. Mid-culm internodes glabrous. Mid-culm nodes glabrous. Lateral branches sparsely branched. Leaf-sheath auricles present. Ligule an eciliate membrane. Leaf-blades flat, 2–25 cm long, 3–10 mm wide. Leaf-blade surface scabrous, glabrous or hairy. Leaf-blade margins scabrous.

Inflorescence
Inflorescence subdigitate, with racemose branches. Racemes 2–12, unilateral, 6–22 cm long. Central inflorescence axis (0–)1.4–2(–9.3) cm long. Rhachis narrowly winged, angular, glabrous on surface or with scattered hairs, scabrous on margins. Spikelet packing imbricate or approximate, 30% of their length apart.

Spikelets
Spikelets appressed, in pairs, all alike or heteromorphic (as to indumentum). Pedicels 0.3–0.5 mm long, scabrous. Fertile spikelets 2-flowered, comprising 1 fertile floret, lower floret sterile, upper fertile, without rhachilla extension, elliptic, dorsally compressed, acute, (2–)2.5–3.3(–3.7) mm long, falling entire. Rhachilla internodes brief up to lowest fertile floret.

Glumes
Glumes dissimilar, thinner than fertile lemma. Lower glume ovate, 0.2–0.7 mm long, 10% of length of spikelet. Upper glume lanceolate, dorsally convex in profile, 1.2–2.7 mm long, (50–)60–75% of length of spikelet, membranous, 3-nerved. Upper glume surface pubescent, hairy between nerves. Upper glume apex acute.

Florets
Basal sterile floret 1, without significant palea. Lemma of lower sterile floret elliptic, 2.7–3.8 mm long, 100% of length of spikelet, membranous, 7-nerved, with equidistant nerves or with unevenly spaced nerves, with nerves free at apex, puberulous or pubescent or villous or setose, hairy between nerves, eciliate on margins or ciliate on margins, acute. Fertile lemma elliptic, 2–3.8 mm long, cartilaginous, much thinner on margins, grey or dark brown, 3-nerved. Lemma surface striate. Lemma margins flat, covering most of palea, ciliate. Lemma apex acute, muticous. Palea cartilaginous. Anthers 3.

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

Australian Distribution:
Western Australia, Northern Territory, South Australia, Queensland, New South Wales, Victoria, Tasmania.

Western Australia: Gardner, Fitzgerald, Hall, Dampier, Fortescue, Austin, Irwin, Drummond, Dale, Menzies, Eyre. Northern Territory: Darwin & Gulf, Victoria River, Barkly Tableland, Central Australia North, Central Australia South. South Australia: Gairdner-Torrens Basin, Flinders Ranges, Eastern, Eyre Peninsula, Northern Lofty, Murray, Yorke Peninsula, Southern Lofty, Kangaroo Island, South-eastern. Queensland: Burke, Burnett, Cook, Darling Downs, Gregory North, Leichhardt, Maranoa, Mitchell, Moreton, North Kennedy, Port Curtis, South Kennedy, Warrego, Wide Bay. New South Wales: North Coast, Central Coast, South Coast, Northern Tablelands, Central Tablelands, Southern Tablelands, North-Western Slopes, Central-Western Slopes, North-Western Plains, South-Western Plains, North Far Western Plains, South Far Western Plains. Victoria: Riverina, Midlands. Tasmania: East Coast.

Classification. (GPWG 2001):
Panicoideae: Paniceae

Notes
Native. This aggressive weed has the potential of occurring anywhere in Australia.

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