Themeda avenacea

HABIT Perennial; caespitose. Butt sheaths woolly. Culms robust; 100–200 cm long; 2–4 mm diam.; 2–3 -noded. Culm-nodes glabrous, or pubescent. Ligule an eciliate membrane. Leaf-blade base simple, or tapering to the midrib. Leaf-blades 15–100 cm long; 1–1.5 mm wide. Leaf-blade surface scaberulous. Leaf-blade margins scabrous. Leaf-blade apex attenuate.

INFLORESCENCE Synflorescence compound; linear; 15–100 cm long. Inflorescence composed of racemes; terminal and axillary; subtended by a spatheole; enclosed. Spatheole linear, or lanceolate; 3–9 cm long; scarious; green, or purple; without tubercles. Peduncle 1–2 cm long; pubescent above.

Racemes 1; single; cuneate; bearing few fertile spikelets; bearing 1–2 fertile spikelets on each. Rhachis fragile at the nodes.

Spikelets in pairs, or in threes (basal paired). Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster, or 2 in the cluster. Pedicels oblong; 0.5 mm long.

STERILE SPIKELETS Basal sterile spikelets well-developed; 4 in number; forming an involucre about the fertile; subsessile; male; linear, or lanceolate; 20–30 mm long; larger than fertile. Basal sterile spikelet glumes chartaceous; lower glume muticous.

Companion sterile spikelets well-developed; containing empty lemmas; linear, or lanceolate; symmetrical, or asymmetrical; 20–30 mm long; longer than fertile; separately deciduous. Companion sterile spikelet callus linear. Companion sterile spikelet glumes chartaceous; thinner on margins; winged on margins; smooth; glabrous. Companion sterile spikelet lemmas 2; enclosed by glumes.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets oblong; subterete; 13–17 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus linear; 5–7 mm long; bearded; base pungent; attached obliquely.

GLUMES Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume oblong; 1 length of spikelet; cartilaginous; much thinner on margins; without keels; 11 -veined. Lower glume surface villous. Lower glume hairs dark brown. Lower glume apex obtuse. Upper glume oblong; cartilaginous; 3 -veined. Upper glume surface villous. Upper glume hairs dark brown.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate; hyaline; 1 -veined; without lateral veins. Fertile lemma linear; hyaline; without keel; 1 -veined. Lemma apex entire; awned; 1 -awned. Principal lemma awn apical; geniculate; 40–100 mm long overall; with twisted column. Column of lemma awn hirsute. Palea absent or minute.

FLOWER Anthers 3; 4 mm long.

DISTRIBUTION Australasia: Australia.

NOTES Andropogoneae. Vickery.

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