Common name
Crabgrass
Summer Grass

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

sanguinalis- from the Latin sanguineus (dull-red) and -alis (pertaining to). Foliage or inflorescence purplish.

Published in
Fl. Carn. 2nd edn, 1: 52 (1772).

Habit
Annual. Stolons absent. Culms decumbent or prostrate, 10–60 cm tall, 2–8-noded, rooting from lower nodes. Mid-culm internodes glabrous. Mid-culm nodes glabrous or bearded. Lateral branches sparsely branched. Leaf-sheaths pilose. Leaf-sheath auricles absent, or present. Ligule an eciliate membrane, 1–2 mm long. Leaf-blades flat, 3–17 cm long, 2–14 mm wide. Leaf-blade surface smooth or scabrous, hairy. Leaf-blade margins scabrous.

Inflorescence
Inflorescence digitate or subdigitate, with racemose branches. Racemes 4–10, unilateral, 4–18 cm long. Central inflorescence axis 0.5–3 cm long. Rhachis narrowly winged, angular, scabrous on margins. Spikelet packing imbricate.

Spikelets
Spikelets appressed, in pairs. Pedicels 0.3–0.6 mm long, scabrous. Fertile spikelets 2-flowered, comprising 1 fertile floret, lower floret sterile, upper fertile, without rhachilla extension, elliptic, dorsally compressed, acute, 2.5–3.3 mm long, falling entire. Rhachilla internodes brief up to lowest fertile floret.

Glumes
Glumes one (the lower absent or obscure) or two, thinner than fertile lemma. Lower glume 0.2–0.37 mm long. Upper glume lanceolate, dorsally convex in profile, 1.2–1.6 mm long, 30–50% of length of spikelet, membranous, 3-nerved. Upper glume surface glabrous or pubescent, hairy between nerves. Upper glume apex obtuse.

Florets
Basal sterile floret 1, without significant palea. Lemma of lower sterile floret elliptic, 2.6–3.2 mm long, 100% of length of spikelet, membranous, 7-nerved, with equidistant nerves, with nerves free at apex, scabrous, rough on nerves, puberulous, hairy between nerves, acute. Fertile lemma elliptic, 2.4–3.3 mm long, cartilaginous, much thinner on margins. Lemma surface striate. Lemma margins flat, covering most of palea. Lemma apex acute, muticous. Palea cartilaginous. Anthers 3, 0.6 mm long. Hilum elliptic.

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

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

Western Australia: Drummond, Dale, Menzies, Warren, Roe, Avon. South Australia: Gairdner-Torrens Basin, Flinders Ranges, Eastern, Eyre Peninsula, Northern Lofty, Murray, Yorke Peninsula, Southern Lofty, South-eastern. Queensland: Darling Downs, Warrego, Maranoa. New South Wales: North Coast, Central Coast, South Coast, Northern Tablelands, Central Tablelands, Southern Tablelands, North-Western Slopes, Central-Western Slopes, South-Western Slopes, North-Western Plains, South-Western Plains, South Far Western Plains. Victoria: Murray Mallee, Lowan Mallee, Wimmera, Wannon, Grampians, Riverina, Midlands, Victorian Volcanic Plain, Otway Plain, Eastern Highlands, Gippsland Plains, East Gippsland. Tasmania: North East, Midlands, East Coast.

Classification. (GPWG 2001):
Panicoideae: Paniceae

Notes
Native. A common weed of temperate areas, preferring loamy disturbed habitats. Flowers mostly Jan.–Apr.

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