Common name
Columbus Grass

Derivation
Sorghum Moench, Methodus 207 (1794), nom. cons.; the Indian name for this genus.

almum- Latin for nourishing. A nutritious forage grass.

Published in
Revista Argent. Agron. 10: 361 (1943).

Habit
Perennial. Rhizomes short. Culms erect, 200–320 cm tall, 6–10 mm diam., 8–10-noded. Mid-culm internodes solid, 7–40 cm long, smooth, glabrous. Mid-culm nodes pubescent. Lateral branches simple. Leaves cauline. Leaf-sheaths smooth, glabrous on surface. Ligule a fringed membrane, 2.5–5.5 mm long. Leaf-blades 30–100 cm long, 25–40 mm wide. Leaf-blade surface smooth, glabrous. Leaf-blade margins scaberulous. Leaf-blade apex attenuate.

Inflorescence
Inflorescence terminal or terminal and axillary. Panicle open, pyramidal, 20–60 cm long, 8–25 cm wide. Primary panicle branches 4–9 -nate, whorled at most nodes, 10–30 cm long. Rames 1.2–2.5 cm long, bearing 1–5 fertile spikelets on each. Rhachis fragile at the nodes, ciliate on margins. Rame internodes filiform. Rame internode tip transverse, cupiliform.

Spikelets
Spikelets in pairs, one sessile and fertile and the other (companion) spikelet pedicelled. Pedicels filiform, 3–3.5 mm long, ciliate. Companion spikelets developed, male, lanceolate, 5 mm long, shorter than fertile or as long as fertile, persistent or separately deciduous. Companion spikelet glumes chartaceous, 9-nerved, muticous. Companion spikelet lemmas enclosed by glumes. Fertile spikelets 2-flowered, comprising 1 fertile floret, lower floret sterile, upper fertile, without rhachilla extension, lanceolate or elliptic or ovate, dorsally compressed, 5.5–6.5 mm long, 2–5 mm wide, falling entire, deciduous with accessory branch structures. Spikelet callus 3.8 mm long, pubescent, base obtuse.

Glumes
Glumes dissimilar, with lower wider than upper, firmer than fertile lemma. Lower glume ovate, 100% of length of spikelet, coriaceous, dark brown, 2-keeled, winged on keel, 9–11-nerved. Lower glume surface flat. Lower glume surface pubescent, hairy below. Lower glume hairs 0.5–0.8 mm long. Lower glume apex dentate or lobed, 3-fid. Upper glume ovate, coriaceous. Upper glume surface pubescent, hairy below.

Florets
Basal sterile floret 1, without significant palea. Lemma of lower sterile floret elliptic, hyaline, 2-nerved, ciliolate on margins. Fertile lemma elliptic, hyaline, 1-nerved. Lemma margins ciliolate. Lemma apex entire or dentate, 2-fid, muticous or 1-awned. Median (principal) awn from a sinus, geniculate, 8–10 mm long overall, with a twisted column, deciduous. Anthers 3, 2–2.5 mm long. Ovary glabrous. Grain with adherent pericarp, obovoid, 3–3.8 mm long, dark brown, glabrous. Embryo 50% of length of grain.

Continental Distribution:
Australasia, South America.

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

Western Australia: Gardner, Roe, Coolgardie. Northern Territory: Darwin & Gulf, Barkly Tableland, Central Australia South. South Australia: North-western, Gairdner-Torrens Basin. Queensland: Cook, North Kennedy, South Kennedy, Port Curtis, Leichhardt, Burnett, Wide Bay, Darling Downs, Moreton, Gregory North, Mitchell, Maranoa. New South Wales: North Coast, Central Coast, South Coast.

Classification. (GPWG 2001):
Panicoideae: Andropogoneae

Notes
Cultivated widely as a forage grass, but has the tendency to escape and become weedy. Flowers Dec–July.