GrassBase - The Online World Grass Flora

Descriptions

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

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

Arthraxon typicus

HABIT Annual. Culms decumbent; 50–100 cm long; rooting from lower nodes. Culm-nodes glabrous, or bearded. Leaf-sheaths outer margin hairy. Leaf-sheath oral hairs ciliate. Ligule a ciliolate membrane. Leaf-blade base amplexicaul. Leaf-blades lanceolate, or ovate; 2–5 cm long; 10–12 mm wide. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence composed of racemes. Peduncle glabrous.

Racemes 6–10; digitate; 3–7 cm long. Rhachis fragile at the nodes; ciliate on margins. Rhachis internodes linear.

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

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, or ovate; laterally compressed; 4.5–5.5 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; 7–9 -veined. Lower glume surface convex; spinose; rough on flanks. Lower glume apex acute. Upper glume lanceolate; chartaceous; 1-keeled; keeled above; 3 -veined. Upper glume primary vein ciliate. Upper glume margins ciliolate. Upper glume apex acute.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate; 3–3.5 mm long; hyaline. Fertile lemma lanceolate; 4.25–5.25 mm long; hyaline; without keel; 1 -veined. Lemma apex lobed; 2 -fid; awned; 1 -awned. Principal lemma awn dorsal; arising 0.2 way up back of lemma; geniculate; 6–8 mm long overall; with twisted column. Column of lemma awn glabrous. Palea absent or minute.

FLOWER Anthers 2, or 3; 3 mm long.

FRUIT Caryopsis with adherent pericarp.

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

NOTES Andropogoneae. Fl Assam 1993.

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