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 santapaui

HABIT Annual. Culms rambling; 15–30 cm long. Culm-nodes pubescent. Leaf-sheaths antrorsely scabrous; glabrous on surface, or pilose; with tubercle-based hairs. Ligule a fringe of hairs. Leaf-blade base amplexicaul. Leaf-blades lanceolate; 2–4 cm long; 5–10 mm wide; flaccid. Leaf-blade surface pilose; with tubercle-based hairs. Leaf-blade margins tuberculate-ciliate. Leaf-blade apex acute.

INFLORESCENCE Inflorescence composed of racemes. Peduncle pubescent above.

Racemes 2–3; paired, or digitate; 3 cm long. Rhachis fragile at the nodes; ciliate on margins. Rhachis internodes filiform; 3.5 mm long.

Spikelets in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels filiform; 3 mm long; 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; laterally compressed; 7.5 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus 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 -veined. Lower glume surface scabrous, or spinose; rough above. Upper glume lanceolate; chartaceous; 1-keeled; keeled above; 3 -veined. Upper glume surface scabrous; pilose; hairy above. Upper glume apex acute.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret oblong; 3 mm long; hyaline; 0 -veined; without midvein; without lateral veins. Fertile lemma lanceolate; 3 mm long; hyaline; without keel; 1 -veined. Lemma apex dentate; 2 -fid; acute; awned; 1 -awned. Principal lemma awn dorsal; arising 0.2 way up back of lemma; geniculate; 18 mm long overall; with twisted column. Column of lemma awn 8 mm long; glabrous. Palea absent or minute.

FLOWER Anthers 2; 0.8 mm long.

FRUIT Caryopsis with adherent pericarp.

DISTRIBUTION Asia-tropical: India.

NOTES Andropogoneae. Bor 1993.

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