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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.
Trisetum irazuense
HABIT Perennial. Culms erect, or geniculately ascending; 45–105 cm long; 1–2 mm diam.; without nodal roots, or rooting from lower nodes. Culm-internodes distally glabrous, or pubescent; with reflexed hairs. Culm-nodes constricted; brown. Lateral branches lacking. Leaf-sheaths pilose; with reflexed hairs. Ligule an eciliate membrane; 1–3 mm long. Leaf-blades 10–33 cm long; 2–5 mm wide. Leaf-blade surface pilose; hairy on both sides.
INFLORESCENCE Inflorescence a panicle.
Panicle open; linear; nodding; 13–30 cm long; 1–3 cm wide; contracted about secondary branches. Primary panicle branches ascending; 3–6 cm long. Panicle branches scabrous.
Spikelets solitary. Fertile spikelets pedicelled.
FERTILE SPIKELETS Spikelets comprising 2–4 fertile florets; with a barren rhachilla extension. Spikelets oblong; laterally compressed; 6–9 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes 1.7–2 mm long; pilose; hairy all along but hairs longer above; with 1.5 mm long hairs. Floret callus pubescent. Floret callus hairs 0.5 mm long.
GLUMES Glumes persistent; similar; shorter than spikelet; thinner than fertile lemma; shiny; gaping. Lower glume lanceolate; 3–5 mm long; 0.75 length of upper glume; membranous; 1-keeled; 1 -veined. Lower glume primary vein scabrous. Lower glume lateral veins absent. Lower glume apex acute. Upper glume obovate; 3.8–6.5 mm long; 0.9–1.1 length of adjacent fertile lemma; membranous; with hyaline margins; 1-keeled; 3 -veined. Upper glume apex acute.
FLORETS Fertile lemma lanceolate; 4.3–6 mm long; membranous; shiny; keeled; 5 -veined. Lemma surface scabrous; rugose. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn dorsal; arising 0.66 way up back of lemma; geniculate; 6–9 mm long overall; with twisted column. Palea gaping; 0.9 length of lemma; hyaline.
FLOWER Anthers 3; 1–1.3 mm long. Ovary glabrous.
FRUIT Caryopsis with adherent pericarp. Hilum punctiform. Endosperm soft.
DISTRIBUTION North America: Mexico. South America: Mesoamericana, northern South America, and western South America.
NOTES Aveneae. Fl Costa Rica 1994.
Please cite this publication as detailed in How to Cite Version: 3rd February 2016.
