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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.
Helictotrichon occidentale
HABIT Perennial; caespitose; clumped loosely. Rhizomes absent, or short. Basal innovations intravaginal. Culms erect, or geniculately ascending; 50–90 cm long; 1–2 -noded. Culm-internodes smooth. Culm-nodes brown. Leaf-sheaths open for most of their length; smooth. Ligule an eciliate membrane, or a ciliolate membrane; 2.5–7 mm long; 0.8–2 mm long on basal shoots. Leaf-blades conduplicate; 15–40 cm long; 1.8–3.5 mm wide. Leaf-blade venation with 10–18 secondary veins. Leaf-blade surface papillose; rough abaxially.
INFLORESCENCE Inflorescence a panicle; comprising 8–30 fertile spikelets.
Panicle open; linear; 5–15 cm long. Primary panicle branches bearing 1–3 fertile spikelets on each lower branch. Panicle branches scabrous.
Spikelets solitary. Fertile spikelets pedicelled.
FERTILE SPIKELETS Spikelets comprising 3–6 fertile florets; with diminished florets at the apex. Spikelets lanceolate; laterally compressed; 12–20 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes 1–1.5 mm long; pilose; with 2–2.5 mm long hairs. Floret callus pubescent. Floret callus hairs 1.5 mm long.
GLUMES Glumes persistent; similar; shorter than spikelet; thinner than fertile lemma. Lower glume elliptic; 9–13 mm long; 0.9 length of upper glume; membranous; 1-keeled; 3 -veined. Lower glume primary vein scabrous. Lower glume apex acute. Upper glume elliptic; 11–14 mm long; 1 length of adjacent fertile lemma; membranous; 1-keeled; 3–5 -veined. Upper glume primary vein scabrous. Upper glume apex acute.
FLORETS Fertile lemma obovate; 11–16 mm long; cartilaginous; dark brown; without keel; 7 -veined. Lemma lateral veins excurrent. Lemma surface puberulous; hairy below. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn dorsal; arising 0.5 way up back of lemma; geniculate; 10–20 mm long overall; with twisted column. Column of lemma awn 2–7 mm long. Palea 8–11 mm long. Palea keels ciliolate; adorned all along, or in the middle; with 1 of their length adorned, or 0.33 of their length adorned. Apical sterile florets resembling fertile though underdeveloped.
FLOWER Lodicules 2; 1.5–2.5 mm long. Anthers 3; 4–5 mm long. Ovary pubescent on apex.
DISTRIBUTION Europe: southwestern.
NOTES Aveneae. Roser 2007.
Please cite this publication as detailed in How to Cite Version: 3rd February 2016.
