Sorghum laxiflorum

HABIT Annual. Culms erect, or geniculately ascending; 100–200 cm long; without nodal roots, or with prop roots. Culm-internodes distally pruinose. Culm-nodes pubescent, or bearded. Leaves cauline. Ligule a ciliolate membrane; 1–2 mm long. Leaf-blades 3–16 mm wide; stiff. Leaf-blade surface glabrous, or hirsute; with tubercle-based hairs. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence a panicle with branches tipped by a raceme.

Panicle contracted; elliptic; 7–17 cm long; 3–4 cm wide. Primary panicle branches not whorled; moderately divided; 1–3 cm long. Panicle branches glabrous, or pilose; glabrous in axils, or bearded in axils.

Racemes 0.8–1.2 cm long; bearing few fertile spikelets; bearing (1–)2(–3) fertile spikelets on each. Rhachis fragile at the nodes; ciliate on margins. Rhachis internodes filiform; 3.6–4 mm long. Rhachis internode tip oblique; cupuliform.

Spikelets in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels filiform; ciliate.

STERILE SPIKELETS Companion sterile spikelets well-developed; comprising 2 unequal glumes without lemmas; linear; 4.3–5 mm long; shorter than fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; 6–8 -veined; pubescent; muticous.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets oblanceolate; dorsally compressed; 5.3–6.6 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus 0.2–0.3 mm long; bearded; base obtuse. Spikelet callus hairs white; 0.25 length of spikelet.

GLUMES Glumes dissimilar; with lower wider than upper; exceeding apex of florets; firmer than fertile lemma. Lower glume ovate; 1 length of spikelet; coriaceous; dark brown, or black; without keels; keel-less except near apex; 11 -veined. Lower glume surface villous; inner surface glabrous. Lower glume hairs white. Lower glume apex acute. Upper glume ovate; coriaceous; dark brown, or black; without keels; 7 -veined. Upper glume surface villous. Upper glume hairs white.

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; 3–4 mm long; hyaline; 3 -veined. Lemma margins ciliate. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 2.5–4.3 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; 1–1.3 mm long.

FRUIT Caryopsis with adherent pericarp; ellipsoid, or obovoid; 3 mm long.

DISTRIBUTION Asia-tropical: Malesia and Papuasia. Australasia: Australia.

NOTES Andropogoneae. Lazarides.

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