Arthraxon hispidus

HABIT Annual; mat forming. Culms rambling; slender; 7–60(–100) cm long; 0.3–1 mm diam.; rooting from lower nodes. Culm-internodes 1–6 cm long. Culm-nodes pubescent. Leaf-sheaths glabrous on surface, or pilose, or hispid; with tubercle-based hairs; outer margin glabrous, or hairy. Ligule a ciliolate membrane; 0.5–3 mm long. Leaf-blade base amplexicaul. Leaf-blades lanceolate, or ovate; 1–8 cm long; 3–25 mm wide. Leaf-blade surface glabrous, or pilose; sparsely hairy; hairy on both sides. Leaf-blade margins tuberculate-ciliate; hairy all along, or at base. Leaf-blade apex acute.

INFLORESCENCE Inflorescence composed of racemes.

Racemes 2–50; digitate; 1.5–5 cm long. Rhachis fragile at the nodes; glabrous on margins, or ciliate on margins. Rhachis hairs (0.5–)0.66–0.75 mm long. Rhachis internodes filiform to linear; 2–6 mm long.

Spikelets in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels linear; 0.1–2 mm long; glabrous, or 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; 3–8 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus glabrous, or pubescent; base truncate; attached transversely.

GLUMES Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume lanceolate; 1 length of spikelet; chartaceous; much thinner on margins; without keels; 7–9 -veined. Lower glume surface convex; spinose; rough on veins. Lower glume apex obtuse. Upper glume lanceolate; chartaceous; 1-keeled; keeled above; 3–5 -veined. Upper glume primary vein scaberulous. Upper glume apex acute, or obtuse.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret oblong; 0.66 length of spikelet; hyaline; 2 -veined; obtuse. Fertile lemma oblong; 2–6 mm long; hyaline; without keel; 1 -veined. Lemma apex acute; muticous, or awned; 1 -awned. Principal lemma awn dorsal; arising 0.2 way up back of lemma; geniculate; 0–20 mm long overall; with a straight or slightly twisted column, or with twisted column. Column of lemma awn glabrous. Palea absent or minute.

FLOWER Anthers 2; 0.5–1 mm long.

FRUIT Caryopsis with adherent pericarp; fusiform, or oblong; 3.5–5 mm long.

DISTRIBUTION Africa: west tropical, west-central tropical, northeast tropical, east tropical, southern tropical, and western Indian ocean. Asia-temperate: Soviet far east, Soviet Middle Asia, Caucasus, western Asia, Arabia, China, Mongolia, and eastern Asia. Asia-tropical: India, Indo-China, Malesia, and Papuasia. Australasia: Australia. Pacific: north-central. North America: north-central USA, northeast USA, southeast USA, and Mexico. South America: Mesoamericana, Caribbean, northern South America, and western South America.

NOTES Andropogoneae. Fl China 2005.

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