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.

Poa nervosa

HABIT Perennial; caespitose; clumped loosely. Rhizomes elongated. Butt sheaths herbaceous. Culms erect; 20–85 cm long. Culm-internodes terete. Leaf-sheaths tubular for much of their length; with 0.5–0.9 of their length closed; without keel, or keeled; striately veined; puberulous. Ligule an eciliate membrane; 1–3 mm long; scaberulous on abaxial surface; truncate, or obtuse. Leaf-blades flat, or conduplicate; 5–10 cm long; 1.5–3 mm wide; 1–6 cm long at summit of culm; light green. Leaf-blade surface smooth, or scaberulous; rough adaxially; glabrous.

INFLORESCENCE Dioecious. Inflorescence a panicle.

Panicle open; ovate; nodding; 5–13 cm long. Primary panicle branches ascending, or spreading; 2–4 -nate; bearing 3–8 fertile spikelets on each lower branch. Panicle branches scabrous.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 2–8 fertile florets; with diminished florets at the apex. Spikelets oblong; laterally compressed; 5–11 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes scaberulous. Floret callus glabrous.

GLUMES Glumes persistent; similar; shorter than spikelet. Lower glume oblong; 0.9 length of upper glume; membranous; 1-keeled. Lower glume primary vein scaberulous. Lower glume apex acute. Upper glume lanceolate; 0.66 length of adjacent fertile lemma; membranous; 1-keeled; 3 -veined. Upper glume primary vein scaberulous. Upper glume apex acute.

FLORETS Fertile florets female. Fertile lemma oblong; elliptic in profile; 4–6 mm long; membranous; mid-green and dark brown (bronze); tipped with last colour; keeled; 5 -veined. Lemma surface scaberulous, or papillose; glabrous. Lemma apex acute. Palea 0.9 length of lemma. Palea keels ciliolate; adorned above. Palea surface scaberulous. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules 2; membranous. Anthers 3; 3 mm long.

FRUIT Caryopsis with adherent pericarp. Hilum punctiform.

MALE Male inflorescence similar to female. Male spikelets resembling female.

DISTRIBUTION North America: western Canada, northwest USA, southwest USA, and south-central USA.

NOTES Poeae. Soreng 1992.

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