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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 dianthemum
HABIT Perennial; caespitose. Culms geniculately ascending; 18–60 cm long; 1–2 -noded. Culm-nodes glabrous. Leaf-sheaths 3–4 cm long; glabrous on surface. Ligule an eciliate membrane; 1–1.5 mm long; 1 mm long on basal shoots, or 2 mm long on basal shoots; glabrous on abaxial surface; erose. Leaf-blades 5–15 cm long; 1.5–2.5 mm wide. Leaf-blade surface smooth; glabrous. Leaf-blade margins scabrous; glabrous, or ciliate. Leaf-blade apex acuminate.
INFLORESCENCE Inflorescence a panicle. Peduncle pilose above.
Panicle contracted; lanceolate; 4–8 cm long; 1–2 cm wide. Panicle axis pubescent.
Spikelets solitary. Fertile spikelets pedicelled. Pedicels 1.5–4 mm long; scabrous.
FERTILE SPIKELETS Spikelets comprising 2–3 fertile florets; with a barren rhachilla extension. Spikelets oblong; laterally compressed; 6.5–8 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes 0.9–1 mm long; pilose. Floret callus pubescent; obtuse.
GLUMES Glumes persistent; similar; with lower narrower than upper; reaching apex of florets; thinner than fertile lemma; shiny; gaping. Lower glume lanceolate; 6–7.5 mm long; 0.9 length of upper glume; membranous; much thinner on margins; 1-keeled; 1–3 -veined. Lower glume primary vein scabrous. Lower glume lateral veins absent, or obscure. Lower glume apex setaceously attenuate. Upper glume lanceolate; 6.5–8 mm long; 1.2–1.3 length of adjacent fertile lemma; membranous; with hyaline margins; 1-keeled; 3 -veined. Upper glume primary vein scabrous. Upper glume apex setaceously attenuate.
FLORETS Fertile lemma elliptic; 5.6–6.3 mm long; membranous; shiny; keeled; 5 -veined. Lemma midvein scaberulous. Lemma surface glabrous. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn dorsal; arising 0.66–0.75 way up back of lemma; geniculate; 3.5–7 mm long overall; with a straight or slightly twisted column. Palea gaping; 4.2–4.5 mm long; hyaline. Palea keels scaberulous.
FLOWER Lodicules 2; 0.6–0.8 mm long. Anthers 3; 0.8 mm long. Ovary glabrous.
FRUIT Caryopsis with adherent pericarp.
DISTRIBUTION South America: southern South America.
NOTES Aveneae. Finot et al 2006.
Please cite this publication as detailed in How to Cite Version: 3rd February 2016.
