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Descriptions

W.D. Clayton, M. Vorontsova, K.T. Harman & H. Williamson

© Copyright The Board of Trustees, Royal Botanic Gardens, Kew.

Andropogon aridus

HABIT Perennial; cushion forming. Culms 20–25 cm long. Ligule an eciliate membrane. Leaf-blades filiform; terete; 3–5 cm long; 1 mm wide.

INFLORESCENCE Inflorescence composed of racemes; terminal.

Racemes 1–2; single, or paired; 1–3 cm long. Rhachis fragile at the nodes; ciliate on margins. Rhachis hairs 5 mm long. Rhachis internodes linear. Rhachis internode tip transverse; cupuliform; with simple rim.

Spikelets appressed; in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels linear; ciliate; hairy all along but hairs longer above; with 5 mm long hairs.

STERILE SPIKELETS Companion sterile spikelets well-developed; male; lanceolate; dorsally compressed; 5 mm long; shorter than fertile. Companion sterile spikelet glumes chartaceous; acute; 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; 6–6.5 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus oblong; 1 mm long; bearded; base obtuse; inserted.

GLUMES Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume elliptic; 1 length of spikelet; chartaceous; 2-keeled; keeled laterally; winged on keel; winged near apex. Lower glume intercarinal veins distinct; 4 in number. Lower glume surface convex; pilose; hairy below. Lower glume apex dentate; 2 -fid. Upper glume lanceolate; chartaceous; 1-keeled. Upper glume apex acute; muticous.

FLORETS Basal sterile florets barren; with palea. Lemma of lower sterile floret lanceolate; 3 mm long; hyaline; 2 -veined. Palea of lower sterile floret 0.5 length of lemma. Fertile lemma lanceolate; 4.5 mm long; hyaline; without keel. Lemma apex lobed; 2 -fid; incised 0.5 of lemma length; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 15 mm long overall; with twisted column. Column of lemma awn glabrous. Palea 0.75 length of lemma.

DISTRIBUTION Africa: northeast tropical.

NOTES Andropogoneae. WDC.

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