Trisetum gracile

HABIT Perennial; caespitose; clumped densely. Butt sheaths pubescent; persistent and investing base of culm; with compacted dead sheaths. Culms 4–15 cm long. Culm-internodes distally glabrous. Leaf-sheaths inflated; striately veined; glabrous on surface. Ligule an eciliate membrane. Leaf-blades curved; filiform; conduplicate; 0.8–3 cm long; 1 mm wide; stiff; grey-green. Leaf-blade venation prominent. Leaf-blade surface puberulous; hairy adaxially. Leaf-blade margins unthickened.

INFLORESCENCE Inflorescence a panicle; comprising 15–25 fertile spikelets.

Panicle open; ovate; dense; 2 cm long; 1.2 cm wide. Panicle branches scabrous.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 2–3 fertile florets; with a barren rhachilla extension. Spikelets oblong; laterally compressed; 4–7 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes pilose; with 1 mm long hairs. Floret callus pubescent.

GLUMES Glumes persistent; similar; reaching apex of florets; thinner than fertile lemma; shiny; gaping. Lower glume lanceolate; 1 length of upper glume; membranous; 1-keeled; 1 -veined. Lower glume lateral veins absent. Lower glume apex acute. Upper glume lanceolate; 0.9–1 length of adjacent fertile lemma; membranous; 1-keeled; 3 -veined. Upper glume apex acute.

FLORETS Fertile lemma oblong; 3.5–5 mm long; membranous; shiny; keeled; 5 -veined. Lemma surface glabrous, or pubescent; hairy below. Lemma apex dentate; 2 -fid; incised 0.15 of lemma length; awned; 3 -awned. Principal lemma awn dorsal; arising 0.33–0.5 way up back of lemma; geniculate; 5 mm long overall; with twisted column. Lateral lemma awns 1 mm long. Palea gaping; hyaline.

FLOWER Anthers 3; 2.5 mm long.

FRUIT Caryopsis with adherent pericarp. Hilum punctiform.

DISTRIBUTION Europe: southwestern.

NOTES Aveneae. Fl Eur 1997.

Please cite this publication as detailed in How to Cite Version: 3rd February 2016.