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.

Muhlenbergia arsenei

HABIT Perennial; caespitose; clumped loosely. Rootstock evident. Rhizomes short. Culms erect, or geniculately ascending; 10–45 cm long. Culm-internodes distally pubescent (below nodes). Leaves mostly basal. Leaf-sheaths puberulous. Ligule an eciliate membrane; 1–1.5 mm long; erose. Leaf-blades ascending, or spreading; flat, or involute; 1–6 cm long; 1–2 mm wide. Leaf-blade surface scabrous; rough abaxially; pubescent; hairy adaxially.

INFLORESCENCE Inflorescence a panicle.

Panicle open; linear; 5–11 cm long. Primary panicle branches appressed, or ascending; 3–4 cm long.

Spikelets appressed; solitary. Fertile spikelets pedicelled. Pedicels pubescent.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension. Spikelets lanceolate; laterally compressed; 3.5–5 mm long; breaking up at maturity; disarticulating below each fertile floret.

GLUMES Glumes persistent; similar; shorter than spikelet, or exceeding apex of florets. Lower glume oblong; 2.5–4 mm long; 1 length of upper glume; membranous; without keels; 1 -veined. Lower glume lateral veins absent. Lower glume surface scabrous; rough above. Lower glume apex acuminate to setaceously attenuate. Upper glume oblong; 2.5–4 mm long; 0.75–1 length of adjacent fertile lemma; membranous; without keels; 1 -veined. Upper glume lateral veins absent. Upper glume surface scabrous; rough above. Upper glume apex acuminate to setaceously attenuate.

FLORETS Fertile lemma lanceolate; 3.4–5 mm long; membranous; without keel; 3 -veined. Lemma midvein pubescent; hairy below. Lemma margins pubescent; hairy below. Lemma apex acuminate; awned; 1 -awned. Principal lemma awn 10–20 mm long overall. Palea 1 length of lemma; 2 -veined. Palea surface pubescent; hairy on back; hairy below.

FLOWER Lodicules 2; cuneate; fleshy. Anthers 3; 1.5–1.8 mm long; purple.

FRUIT Caryopsis with adherent pericarp; fusiform.

DISTRIBUTION North America: southwest USA, south-central USA, and Mexico.

NOTES Eragrostideae. Gr Baja Cal 1994.

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