Sorghum amplum

HABIT Annual. Culms robust, or of moderate stature; 100–400 cm long; 4–8 mm diam.; 6–8 -noded; without nodal roots, or with prop roots. Culm-internodes distally pruinose. Culm-nodes pubescent, or bearded. Lateral branches lacking, or sparse. Leaf-sheaths glabrous on surface. Ligule a ciliolate membrane; 1.7–3.3 mm long. Leaf-blades 10–18 mm wide. Leaf-blade surface glabrous, or hispid; with tubercle-based hairs.

INFLORESCENCE Inflorescence a panicle with branches tipped by a raceme.

Panicle open; dense; 11–28 cm long. Primary panicle branches 1–15 -nate; simple, or sparsely divided; 3–7 cm long. Panicle axis smooth, or scaberulous. Panicle branches apically expanded; pubescent in axils.

Racemes 1.4–1.8 cm long; bearing a triad of spikelets, or few fertile spikelets; bearing 1(–2) fertile spikelets on each. Rhachis evident, or obsolete; fragile at the nodes; ciliate on margins. Rhachis internodes linear. Rhachis internode tip oblique.

Spikelets in pairs, or in threes. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster, or 2 in the cluster. Pedicels filiform; flattened; 6–7 mm long; ciliate.

STERILE SPIKELETS Companion sterile spikelets well-developed; containing empty lemmas, or male; lanceolate; dorsally compressed; 8.5–10 mm long; as long as fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; 7–9 -veined; puberulous; muticous. Companion sterile spikelet lemmas enclosed by glumes; 8.5–10 mm long.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets elliptic; dorsally compressed; compressed slightly; 7.3–11 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus cuneate; curved; 1–1.5 mm long; base pungent.

GLUMES Glumes dissimilar; with lower wider than upper; exceeding apex of florets; firmer than fertile lemma; dull, or shiny. Lower glume ovate; 1 length of spikelet; cartilaginous; much thinner above; without keels; keel-less except near apex; 7–9 -veined. Lower glume lateral veins with cross-veins. Lower glume surface glabrous, or pilose. Lower glume hairs dark brown; 3–4 mm long. Upper glume ovate; cartilaginous; much thinner above; without keels; 7 -veined. Upper glume surface glabrous, or pubescent.

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; 65–90 mm long overall; with twisted column. Column of lemma awn glabrous. Palea absent or minute.

FLOWER Lodicules 2; oblong; 0.5 mm long; fleshy; ciliate. Anthers 3; 4–4.6 mm long. Stigmas 2. Ovary glabrous.

FRUIT Caryopsis with adherent pericarp; ellipsoid; 5–5.3 mm long; obtuse.

DISTRIBUTION Australasia: Australia.

NOTES Andropogoneae. Lazarides 1993.

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