Sorghum exstans

HABIT Annual. Culms 130–300 cm long; 3–5.5 mm diam.; 5–8 -noded; with prop roots. Culm-internodes mid-green. Culm-nodes constricted, or flush with internodes; glabrous. Lateral branches lacking. Ligule an eciliate membrane; 2–4.5 mm long. Leaf-blades 6–12 mm wide. Leaf-blade surface glabrous, or pilose; with tubercle-based hairs.

INFLORESCENCE Inflorescence a panicle with branches tipped by a raceme.

Panicle open; dense, or loose; 22–34 cm long; 3–5 cm wide. Primary panicle branches 1–14 -nate; simple; 4–7 cm long. Panicle axis smooth, or scaberulous. Panicle branches glabrous in axils; with prominent pulvini.

Racemes 2–2.5 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; 6–8 mm long; ciliate; with dark brown hairs; with 3–3.2 mm long hairs.

STERILE SPIKELETS Companion sterile spikelets well-developed; containing empty lemmas, or male; linear, or lanceolate; dorsally compressed; 10–14 mm long; shorter than fertile; separately deciduous. Companion sterile spikelet glumes cartilaginous; 7–9 -veined; glabrous to pilose; ciliate on margins; acuminate; muticous. 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; 11–15.5 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus cuneate; 3–8 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; cartilaginous, or coriaceous; much thinner above; 2-keeled; keeled above; winged on keel; winged narrowly; 7–9 -veined. Lower glume lateral veins with cross-veins. Lower glume surface glabrous, or pilose; with tubercle-based hairs. Lower glume hairs dark brown. Lower glume apex dentate; 3 -fid. Upper glume ovate; cartilaginous, or coriaceous; much thinner above; without keels; 5–7 -veined. Upper glume surface glabrous, or pilose.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate; hyaline; 2 -veined; acute. Fertile lemma oblong; hyaline; 1 -veined. Lemma apex lobed; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 70–110 mm long overall; with twisted column. Column of lemma awn glabrous. Palea absent or minute.

FLOWER Lodicules 2; oblong; 0.5–0.7 mm long; fleshy; ciliate; hairy on the corners. Anthers 3; 5–6.2 mm long. Stigmas 2. Ovary pubescent on apex.

FRUIT Caryopsis with adherent pericarp; obovoid; dorsally compressed; 4–6 mm long; hairy at apex.

DISTRIBUTION Australasia: Australia.

NOTES Andropogoneae. Lazarides 1993.

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