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 arctica

HABIT Perennial; culms solitary, or caespitose. Rhizomes elongated. Butt sheaths herbaceous. Culms decumbent; 20–60 cm long; wiry. Culm-internodes terete; smooth. Leaf-sheaths with 0.5–0.75 of their length closed; without keel. Ligule an eciliate membrane; 3–7 mm long; glabrous on abaxial surface; obtuse. Leaf-blades flat, or conduplicate; 1–2.5 mm wide; mid-green, or glaucous. Leaf-blade surface glabrous.

INFLORESCENCE Inflorescence a panicle.

Panicle open; lanceolate, or ovate; 4–15 cm long; bearing few spikelets; with spikelets clustered towards branch tips. Primary panicle branches ascending; 2 -nate. Panicle branches scabrous.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 2–3 fertile florets; with diminished florets at the apex. Spikelets ovate; laterally compressed; 5–8 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes smooth. Floret callus woolly.

GLUMES Glumes persistent; similar; shorter than spikelet. Lower glume lanceolate; 0.9 length of upper glume; membranous; much thinner on margins; 1-keeled. Lower glume primary vein smooth. Lower glume apex acute. Upper glume lanceolate; 3.5–6 mm long; 1 length of adjacent fertile lemma; membranous; with hyaline margins; 1-keeled; 3 -veined. Upper glume primary vein smooth. Upper glume apex acute.

FLORETS Fertile lemma elliptic; ovate in profile; 3.5–6 mm long; membranous; keeled; 5 -veined. Lemma midvein ciliate. Lemma lateral veins obscure. Lemma surface villous; hairy on back. Lemma margins ciliate. Lemma apex acute. Palea 0.9 length of lemma. Palea keels ciliolate; adorned above. Palea surface glabrous, or pubescent; hairy on back. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules 2; membranous. Anthers 3; 1.4–2.5 mm long; pallid, or purple.

FRUIT Caryopsis with adherent pericarp. Hilum punctiform.

CLEISTOGENES AND VIVIPARY Vegetative proliferation occurs.

DISTRIBUTION Europe: northern and eastern. Asia-temperate: Siberia, Soviet far east, China, and eastern Asia. North America: Subarctic, western Canada, eastern Canada, northwest USA, southwest USA, and south-central USA. South America: southern South America.

NOTES Poeae. Soreng 1992.

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