Sorghum plumosum

HABIT Perennial. Rhizomes short. Butt sheaths pubescent. Culms erect; 100–300 cm long; 3–6 mm diam.; 4–5 -noded. Culm-nodes glabrous, or pubescent, or bearded. Leaf-sheaths hirsute; with simple hairs, or tubercle-based hairs. Leaf-sheath oral hairs bearded. Ligule a ciliolate membrane, or a ciliate membrane; 1.5–3 mm long. Leaf-blades 15–30 cm long; 4–12 mm wide. Leaf-blade surface glabrous, or hirsute; hairy abaxially, or on both sides. Leaf-blade apex acuminate; filiform.

INFLORESCENCE Inflorescence a panicle with branches tipped by a raceme.

Panicle contracted; linear, or lanceolate; 12.5–32(–45) cm long; 2–4 cm wide. Primary panicle branches 1–8 -nate; not whorled; simple; 3–7 cm long. Panicle branches angular; scabrous; pubescent in axils, or bearded in axils; with prominent pulvini.

Racemes 2–3.5 cm long; bearing few fertile spikelets; bearing (1–)2–4(–6) fertile spikelets on each. Rhachis fragile at the nodes; ciliate on margins. Rhachis internodes filiform; 4–5 mm long. Rhachis internode tip oblique.

Spikelets in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels filiform; 4.5–6 mm long; ciliate.

STERILE SPIKELETS Companion sterile spikelets well-developed; containing empty lemmas; linear; 7–10.5 mm long; as long as fertile; persistent. Companion sterile spikelet glumes chartaceous; 3–7 -veined; villous; acuminate; 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; (6–)8–9(–11) mm long; falling entire; deciduous with accessory branch structures. Spikelet callus cuneate; curved; (0.5–)1.3–2.5(–4) 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; cartilaginous; without keels; keel-less except near apex; 5–7 -veined. Lower glume surface villous. Lower glume apex acute. Upper glume ovate; cartilaginous; without keels; 5–7 -veined. Upper glume surface villous.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret elliptic; 0.8 length of spikelet; hyaline; 2 -veined; ciliolate on margins. Fertile lemma oblong; 2–3 mm long; hyaline; 1 -veined. Lemma margins ciliate. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; (30–)50–70(–100) mm long overall; with twisted column. Column of lemma awn pubescent; hairy on the spiral. Palea absent or minute.

FLOWER Lodicules 2; ciliate. Anthers 3; 3.6–3.8 mm long.

FRUIT Caryopsis with adherent pericarp; obovoid; flattened; 3.3–4.3 mm long.

DISTRIBUTION Asia-tropical: Malesia. Australasia: Australia.

NOTES Andropogoneae. Lazarides.

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