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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 sumatrense
HABIT Perennial; caespitose. Rhizomes short. Butt sheaths glabrous, or pubescent. Culms erect; 40–70 cm long. Culm-internodes terete. Culm-nodes glabrous. Lateral branches lacking. Leaves mostly basal. Leaf-sheaths smooth; glabrous on surface. Ligule an eciliate membrane; 1–2 mm long; pubescent on abaxial surface. Leaf-blades filiform, or linear; convolute; 10–40 cm long; 1–6 mm wide; stiff.
INFLORESCENCE Inflorescence a panicle.
Panicle open, or contracted; oblong; equilateral, or nodding; 7–20 cm long; 4–7 cm wide. Primary panicle branches ascending; 3–6 -nate; 4–6 cm long; bearing 4–8 fertile spikelets on each lower branch; bearing spikelets almost to the base. Panicle axis scabrous. Panicle branches flexuous; scabrous.
Spikelets solitary. Fertile spikelets pedicelled.
FERTILE SPIKELETS Spikelets comprising 2–3 fertile florets; with diminished florets at the apex. Spikelets oblong; laterally compressed; 8–11 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes 2.6–3.1 mm long; pilose; with 1–2 mm long hairs. Floret callus 0.4 mm long; pilose. Floret callus hairs 0.5–1.5 mm long.
GLUMES Glumes persistent; similar; shorter than spikelet; thinner than fertile lemma; shiny. Lower glume lanceolate; 4–8 mm long; 0.66–0.75 length of upper glume; membranous; 1-keeled; 1(–3) -veined. Lower glume lateral veins absent, or obscure. Lower glume surface scabrous; rough on veins. Lower glume apex acute. Upper glume lanceolate; 6–10 mm long; 0.8–1.1 length of adjacent fertile lemma; membranous; 1-keeled; 3 -veined. Upper glume surface scabrous; rough on veins. Upper glume apex acute.
FLORETS Fertile lemma oblong, or ovate; 7–9.3 mm long; cartilaginous; without keel; 5(–7) -veined. Lemma surface scabrous; rough on veins. Lemma apex dentate; 2 -fid; with lobes 0.5 mm long; acute; awned; 1 -awned. Principal lemma awn dorsal; arising 0.6 way up back of lemma; geniculate; 7.5–15 mm long overall; with a straight or slightly twisted column. Column of lemma awn 1.5–3 mm long; puberulous. Palea 1 length of lemma. Palea keels ciliolate; adorned above. Apical sterile florets resembling fertile though underdeveloped.
FLOWER Lodicules 2; 1 mm long. Anthers 3; 2 mm long. Ovary pubescent on apex.
FRUIT Caryopsis with adherent pericarp; hairy at apex. Hilum linear.
DISTRIBUTION Asia-tropical: Malesia.
NOTES Aveneae. Sevenster 1993.
Please cite this publication as detailed in How to Cite Version: 3rd February 2016.
