GrassBase - The Online World Grass Flora


W.D. Clayton, M. Vorontsova, K.T. Harman & H. Williamson

© Copyright The Board of Trustees, Royal Botanic Gardens, Kew.

Poa trinervis

HABIT Perennial; caespitose. Butt sheaths light brown; persistent and investing base of culm. Basal innovations extravaginal. Culms erect; 15–35 cm long. Leaf-sheaths smooth; glabrous on surface. Ligule an eciliate membrane; 0.5–3.25 mm long; scaberulous on abaxial surface; acute. Leaf-blades erect; involute; 4–15 cm long; 0.5–0.7 mm wide; stiff. Leaf-blade surface smooth; glabrous. Leaf-blade apex acute.

INFLORESCENCE Inflorescence a panicle. Peduncle smooth, or scaberulous above.

Panicle open; lanceolate; 4–8.5 cm long; 0.5–2.5 cm wide. Primary panicle branches ascending, or spreading; 1–3 -nate; 1.5–3.2 cm long; bearing 2–15 fertile spikelets on each lower branch. Panicle branches scabrous.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 2 fertile florets; with a barren rhachilla extension. Spikelets ovate; laterally compressed; 2.8–4 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes 0.4–0.5 mm long; smooth. Floret callus glabrous.

GLUMES Glumes persistent; similar; shorter than spikelet. Lower glume elliptic; 2.1–3.1 mm long; 0.75 length of upper glume; membranous; 1-keeled; 1–3 -veined. Lower glume primary vein scabrous. Lower glume lateral veins absent, or distinct. Lower glume surface scabrous. Lower glume apex acute. Upper glume ovate; 2.6–3.5 mm long; 1 length of adjacent fertile lemma; membranous; 1-keeled; 3 -veined. Upper glume primary vein scabrous. Upper glume surface asperulous. Upper glume apex acute.

FLORETS Fertile lemma ovate; 2.5–3.5 mm long; membranous; keeled; 3–7 -veined. Lemma lateral veins obscure. Lemma apex acute. Rhachilla extension 0.5–1 mm long.

FLOWER Lodicules 2; membranous. Anthers 3; 1.3–1.6 mm long.

FRUIT Caryopsis with adherent pericarp; ellipsoid; 1.5 mm long. Hilum punctiform.

DISTRIBUTION Asia-tropical: Papuasia.

NOTES Poeae. Alp Fl N Guin 1994.

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