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Descriptions

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

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

Arthraxon nudus

HABIT Annual; mat forming. Culms rambling; 30–60 cm long; rooting from lower nodes. Culm-nodes pubescent. Lateral branches ample. Leaf-sheaths 2–3 cm long; pilose; outer margin hairy. Ligule a ciliolate membrane; 2 mm long. Leaf-blade base amplexicaul. Leaf-blades lanceolate, or ovate; 1–8 cm long; 3–20 mm wide. Leaf-blade margins scaberulous; ciliate (sparsely). Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence composed of racemes.

Racemes 4–9; borne along a central axis; 1–2.5 cm long. Central inflorescence axis 4–6 cm long. Rhachis fragile at the nodes; glabrous on surface; glabrous on margins. Rhachis internodes linear; 3 mm long; 1 length of fertile spikelet.

Spikelets in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels linear; 1 mm long; glabrous.

STERILE SPIKELETS Companion sterile spikelets represented by barren pedicels.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate; laterally compressed; 3 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus glabrous; base truncate; attached transversely.

GLUMES Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume lanceolate; 1 length of spikelet; chartaceous; without keels; keel-less except near apex; 7 -veined. Lower glume primary vein scaberulous. Lower glume surface convex. Upper glume lanceolate; chartaceous; 1-keeled; keeled above; 3 -veined. Upper glume primary vein scaberulous. Upper glume apex acute.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate; 2 mm long; 0.66 length of spikelet; hyaline; 2 -veined; obtuse. Fertile lemma lanceolate; 2.2 mm long; hyaline; without keel; 1 -veined. Lemma apex acute; awned; 1 -awned. Principal lemma awn dorsal; arising 0.2 way up back of lemma; geniculate; 7 mm long overall; with twisted column. Column of lemma awn glabrous. Palea absent or minute.

FLOWER Anthers 2; 0.5 mm long; yellow.

FRUIT Caryopsis with adherent pericarp.

DISTRIBUTION Asia-temperate: Arabia and China. Asia-tropical: India, Indo-China, and Malesia.

NOTES Andropogoneae. Gilliland 1993.

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