Common name
Scrobic
Ditch Millet

Derivation
Paspalum L., Syst. Nat. 10th edn, 855 (1759); from the Greek paspalos (a kind of millet).

scrobiculatum- from the Latin scrobis (ditch), -ulus (diminutive) and -atus (possessing). Glumes or lemmas furrowed.

Published in
Mant. Pl. 1: 29 (1767).

Common synonyms
Paspalum commersonii Lam.
Paspalum orbiculare G.Forst.

Habit
Perennial, mat forming or tufted. Cataphylls present. Stolons absent or present. Culms erect or geniculately ascending or decumbent, 10–150 cm tall, 1–6 mm diam., 2–17-noded, without nodal roots or rooting from lower nodes. Mid-culm nodes glabrous. Lateral branches sparsely branched. Leaf-sheaths mostly shorter than adjacent culm internode, glabrous on surface. Leaf-sheaths outer margin glabrous. Leaf-sheath auricles absent, or present. Ligule an eciliate membrane, 0.4–3 mm long. Leaf-blade base simple. Leaf-blades 5–40 cm long, 3–15 mm wide. Leaf-blade surface smooth, glabrous. Leaf-blade apex attenuate, filiform.

Inflorescence
Inflorescence compound, a panicle of racemes. Racemes 1–20, spreading, unilateral, 2–15 cm long, 1.7–2.5 mm wide, bearing 30–110 fertile spikelets on each. Central inflorescence axis 0–8 cm long. Rhachis broadly winged, with sharp-edged midrib, 1–2.5 mm wide. Spikelet packing abaxial, regular, 2-rowed.

Spikelets
Spikelets solitary. Pedicels oblong, 0.5–0.9 mm long. Fertile spikelets 2-flowered, comprising 1 fertile floret, lower floret sterile, upper fertile, without rhachilla extension, obovate or orbicular, dorsally compressed, plano-convex, obtuse, 1.4–3 mm long, falling entire.

Glumes
Glume 1 (the lower absent or obscure), thinner than fertile lemma. Upper glume elliptic, 2.1–2.9 mm long, 100% of length of spikelet, hyaline or membranous or chartaceous, dark brown, 5–7-nerved. Upper glume surface glabrous. Upper glume margins eciliate. Upper glume apex obtuse.

Florets
Basal sterile floret 1, without significant palea. Lemma of lower sterile floret similar to upper glume, elliptic, 2.1–2.9 mm long, 100% of length of spikelet, chartaceous, 3–5-nerved, obtuse. Fertile lemma elliptic or orbicular, gibbous, 2.1–2.9 mm long, indurate, dark brown, dull, 5-nerved. Lemma surface striate. Lemma margins involute. Lemma apex obtuse. Palea involute, indurate. Anthers 0.7–1 mm long.

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

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

Western Australia: Gardner, Fitzgerald, Hall. Northern Territory: Darwin & Gulf, Victoria River, Barkly Tableland. Queensland: Cook, Burke, North Kennedy, South Kennedy, Port Curtis, Leichhardt, Wide Bay, Darling Downs, Moreton. New South Wales: North Coast, Central Coast, South Coast.

Classification. (GPWG 2001):
Panicoideae: Paniceae

Notes
Native. Usually associated with damp soils and grazed in moderation. Flowers mostly Dec.–June.