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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 atacamensis
HABIT Annual. Culms erect, or geniculately ascending; weak; (3–)5–10(–15) cm long; 0.3–0.4 mm diam.; without nodal roots. Lateral branches ample. Leaf-sheaths 1–2.4 cm long; glabrous on surface. Ligule an eciliate membrane; 1.5–3.2 mm long; acuminate. Leaf-blades 1.2–7 cm long; 0.7–3 mm wide; flaccid. Leaf-blade surface scaberulous. Leaf-blade margins scabrous.
INFLORESCENCE Inflorescence a panicle.
Panicle open, or contracted; lanceolate, or elliptic; 1–5.4 cm long; 0.4–2.4 cm wide; contracted about primary branches. Primary panicle branches 6–10 in number; appressed, or ascending; 1 -nate; 0.3–1.8 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; 2–3 mm long; breaking up at maturity; disarticulating below each fertile floret.
GLUMES Glumes persistent; similar; shorter than spikelet; thinner than fertile lemma. Lower glume ovate; 1–1.7 mm long; 0.75 length of upper glume; membranous; yellow, or mid-green; 1-keeled; keeled above; 1 -veined. Lower glume primary vein scabrous. Lower glume lateral veins absent. Lower glume apex acute. Upper glume ovate; 1.3–2 mm long; 0.5 length of adjacent fertile lemma; membranous; yellow, or mid-green; 1-keeled; keeled above; 1 -veined. Upper glume primary vein scabrous. Upper glume lateral veins absent. Upper glume apex acute.
FLORETS Fertile lemma lanceolate; 1.8–2.9 mm long; cartilaginous; yellow and grey; mottled with last colour; keeled; keeled above; 3 -veined. Lemma surface pubescent. Lemma hairs 0.1–0.2 mm long. Lemma apex acute, or acuminate; muticous, or awned; 1 -awned. Principal lemma awn 1–2 mm long overall. Palea 1.7–2.8 mm long; cartilaginous; 2 -veined. Palea keels smooth. Palea apex with excurrent keel veins. 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; 1.3–1.5 mm long; light brown.
DISTRIBUTION South America: western South America and southern South America.
NOTES Eragrostideae. Peterson.
Please cite this publication as detailed in How to Cite Version: 3rd February 2016.
