Sorghum brachypodum

HABIT Annual. Culms 100–250 cm long; 2.6–7 mm diam.; 4–6 -noded; without nodal roots. Culm-internodes glaucous; distally pruinose, or glabrous. Culm-nodes glabrous. Ligule an eciliate membrane; 1–2 mm long; scaberulous on abaxial surface. Leaf-blades curled; 4–8 mm wide. Leaf-blade surface smooth, or scaberulous; rough adaxially; glabrous, or pilose (rarely); with tubercle-based hairs.

INFLORESCENCE Inflorescence a panicle with branches tipped by a raceme.

Panicle open; loose; 13–30 cm long; 3–5 cm wide. Primary panicle branches 3–8 -nate; simple; 2–5 cm long. Panicle axis smooth; glabrous. Panicle branches pilose; hairy brown at tip; with prominent pulvini.

Racemes 2–3.5 cm long; bearing a triad of spikelets; bearing 1 fertile spikelets on each. Rhachis obsolete.

Spikelets in threes. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 2 in the cluster. Pedicels filiform; flattened; 6–9 mm long; ciliate.

STERILE SPIKELETS Companion sterile spikelets well-developed; containing empty lemmas, or male; lanceolate; dorsally compressed; 12–20 mm long; as long as fertile; separately deciduous. Companion sterile spikelet glumes membranous, or cartilaginous; 7–10 -veined; glabrous, or pubescent; emarginate, or obtuse; mucronate. Companion sterile spikelet lemmas enclosed by glumes.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets obovate; dorsally compressed; 12.5–18 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus cuneate; 5–10 mm long; base pungent.

GLUMES Glumes dissimilar; with lower wider than upper; exceeding apex of florets; firmer than fertile lemma; shiny. Lower glume ovate; 1 length of spikelet; coriaceous; much thinner above; 2-keeled; keeled above; winged on keel; winged narrowly; winged above; 8 -veined. Lower glume lateral veins with cross-veins. Lower glume surface glabrous. Lower glume margins ciliate. Lower glume apex dentate; 3 -fid. Upper glume ovate; coriaceous; much thinner above; without keels; 7 -veined. Upper glume margins eciliate, or ciliate.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate; hyaline; 2 -veined; acute. Fertile lemma ovate; hyaline; 1 -veined. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 65–130 mm long overall; with twisted column. Column of lemma awn ciliate. Palea absent or minute.

FLOWER Lodicules 2; oblong; 0.6–1 mm long; fleshy; ciliate. Anthers 3; 5–9 mm long. Stigmas 2. Ovary glabrous.

FRUIT Caryopsis with adherent pericarp; ellipsoid, or obovoid; isodiametric; 5–6 mm long; truncate, or obtuse.

DISTRIBUTION Australasia: Australia.

NOTES Andropogoneae. Lazarides 1993.

Please cite this publication as detailed in How to Cite Version: 3rd February 2016.