GrassBase - The Online World Grass Flora


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

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

Muhlenbergia decumbens

HABIT Annual. Culms decumbent; weak; 12–30 cm long; 0.4–0.7 mm diam.; rooting from lower nodes. Lateral branches ample. Leaf-sheaths 1.2–4.6 cm long; glabrous on surface. Ligule an eciliate membrane; 1.6–2.5 mm long; truncate, or obtuse. Leaf-blades 2.5–8 cm long; 0.8–1.4 mm wide. Leaf-blade surface scaberulous. Leaf-blade margins scabrous.

INFLORESCENCE Inflorescence a panicle.

Panicle open, or contracted; lanceolate, or elliptic; (4.5–)8–11 cm long; 1.5–4.5 cm wide; contracted about primary branches. Primary panicle branches 6–10 in number; appressed, or ascending; 1 -nate; 2.5–4.8 cm long; bearing spikelets almost to the base.

Spikelets solitary. Fertile spikelets pedicelled. Pedicels 1–3 mm long; scabrous.

FERTILE SPIKELETS Spikelets comprising 1 fertile florets; without rhachilla extension, or with diminished florets at the apex. Spikelets elliptic; laterally compressed; compressed slightly; 3–4 mm long; breaking up at maturity; disarticulating below each fertile floret.

GLUMES Glumes persistent; similar; shorter than spikelet; thinner than fertile lemma. Lower glume lanceolate; 1.8–2.5 mm long; 0.75 length of upper glume; membranous; grey; 1-keeled; keeled above; 1 -veined. Lower glume primary vein scabrous. Lower glume lateral veins absent. Lower glume apex acuminate; muticous, or awned; 1 -awned. Lower glume awn 0–0.6 mm long. Upper glume ovate; 2.4–3.2 mm long; 0.66–0.8 length of adjacent fertile lemma; membranous; grey; 1-keeled; keeled above; 1 -veined. Upper glume primary vein scabrous. Upper glume lateral veins absent. Upper glume apex acuminate; muticous, or awned; 1 -awned. Upper glume awn 0–0.6 mm long.

FLORETS Fertile lemma lanceolate; 3–3.8 mm long; cartilaginous; dark green, or grey; keeled; keeled above; 3 -veined. Lemma midvein pubescent; hairy below. Lemma margins pubescent; hairy below. Lemma hairs 0.1–0.2 mm long. Lemma apex acuminate; muticous, or awned; 1 -awned. Principal lemma awn 0.2–3 mm long overall. Palea 3–3.7 mm long; cartilaginous; 2 -veined. Palea keels scaberulous. Palea apex awned; awns 0.3–0.6 mm long. Apical sterile florets 1 in number; male; lanceolate.

FLOWER Lodicules 2; cuneate; fleshy. Anthers 3; 0.9–1.1 mm long; green.

FRUIT Caryopsis with adherent pericarp; fusiform; 2–2.3 mm long; light brown.

DISTRIBUTION North America: Mexico.

NOTES Eragrostideae. Peterson.

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