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.

Aristida mexicana

HABIT Perennial; caespitose. Culms erect, or geniculately ascending; 15–30 cm long. Culm-internodes distally pubescent. Lateral branches lacking. Leaf-sheaths longer than adjacent culm internode; scaberulous. Leaf-sheath oral hairs ciliate. Ligule a fringe of hairs. Leaf-blades conduplicate; 10–20 cm long; 1–2 mm wide; glaucous. Leaf-blade surface scabrous; rough on both sides. Leaf-blade margins scabrous. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence a panicle. Peduncle pubescent above.

Panicle open; ovate; effuse; 30 cm long; 20 cm wide; with spikelets clustered towards branch tips. Primary panicle branches spreading; distant; 1 -nate; rebranched near base; 5–10 cm long. Panicle axis pubescent. Panicle branches scabrous; pubescent in axils.

Spikelets solitary. Fertile spikelets pedicelled. Pedicels scabrous.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets lanceolate; subterete; 13 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus evident; 1 mm long; pubescent; acute.

GLUMES Glumes persistent; similar; exceeding apex of florets; thinner than fertile lemma. Lower glume linear; 13 mm long; 1.1 length of upper glume; membranous; 1-keeled; 1 -veined. Lower glume primary vein scabrous. Lower glume lateral veins absent. Lower glume apex acuminate; awned; 1 -awned. Lower glume awn 1 mm long. Upper glume linear; 12 mm long; 1.2 length of adjacent fertile lemma; membranous; 1-keeled; 1 -veined. Upper glume primary vein smooth. Upper glume lateral veins absent. Upper glume apex acuminate; awned; 1 -awned. Upper glume awn 1 mm long.

FLORETS Fertile lemma lanceolate; subterete; 8–10 mm long; coriaceous; without keel; 3 -veined. Lemma midvein scabrous. Lemma apex acuminate; awned; 3 -awned. Principal lemma awn 3-branched; with 15–17 mm long limb; persistent. Lateral lemma awns 15–17 mm long; subequal to principal.

DISTRIBUTION North America: Mexico.

NOTES Aristideae. Henrard 1997.

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