Sorghum interjectum

HABIT Perennial; caespitose; clumped densely. Butt sheaths glabrous, or pubescent, or pilose. Culms robust; 130–250 cm long; 3–7 mm diam.; 4–7 -noded; without nodal roots. Culm-internodes distally pruinose, or glabrous. Culm-nodes pubescent, or bearded. Leaf-sheaths outer margin glabrous, or hairy. Leaf-sheath oral hairs lacking, or bearded. Ligule an eciliate membrane; 2.6–3.7 mm long; pubescent on abaxial surface. Leaf-blades 7–14 mm wide. Leaf-blade surface glabrous to hirsute; with tubercle-based hairs.

INFLORESCENCE Inflorescence a panicle with branches tipped by a raceme.

Panicle open; dense; 30–40 cm long; 2.5–5 cm wide. Primary panicle branches sparsely divided; 3–7.5 cm long. Panicle axis smooth. Panicle branches terete, or flat; smooth, or scaberulous; rough distally; glabrous, or villous; hairy at tip; glabrous in axils, or pubescent in axils.

Racemes bearing few fertile spikelets; 2–4 fertile spikelets on each. Rhachis fragile at the nodes; ciliate on margins. Rhachis internodes linear. Rhachis internode tip oblique.

Spikelets in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels filiform; flattened; 5.5–7 mm long; ciliate.

STERILE SPIKELETS Companion sterile spikelets well-developed; containing empty lemmas, or male; linear; dorsally compressed; 10–13 mm long; shorter than fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; pubescent, or pilose; ciliate on margins; muticous. Companion sterile spikelet lemmas enclosed by glumes.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets elliptic; dorsally compressed; 11–15 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus cuneate; straight, or curved; 3–6 mm long; base pungent.

GLUMES Glumes dissimilar; with lower wider than upper; exceeding apex of florets; firmer than fertile lemma. Lower glume ovate; 1 length of spikelet; coriaceous; much thinner above; without keels; keel-less except near apex; 7–9 -veined. Lower glume lateral veins without connecting veins, or with cross-veins. Lower glume surface pubescent, or pilose; with tubercle-based hairs. Upper glume ovate; coriaceous; much thinner above; without keels; 7–9 -veined. Upper glume lateral veins without cross-veins, or with cross-veins. Upper glume surface pubescent, or pilose; with tubercle-based hairs.

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; 50–92 mm long overall; with twisted column. Column of lemma awn glabrous. Palea absent or minute.

FLOWER Lodicules 2; oblong; 0.6–1 mm long; fleshy; ciliate; hairy across the apex. Anthers 3; 4.2 mm long. Stigmas 2. Ovary glabrous.

FRUIT Caryopsis with adherent pericarp; obovoid; 3.5–4.5 mm long; truncate.

DISTRIBUTION Australasia: Australia.

NOTES Andropogoneae. Lazarides 1993.

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