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 arnowiae

HABIT Perennial; culms solitary, or caespitose; clumped loosely. Rhizomes short. Culms geniculately ascending, or decumbent; 15–80 cm long. Leaf-sheaths tubular for much of their length; with 0.5–0.9 of their length closed; keeled; smooth, or scaberulous; glabrous on surface. Ligule an eciliate membrane; 0.5–4 mm long; glabrous on abaxial surface, or scaberulous on abaxial surface; entire, or erose; truncate, or obtuse. Leaf-blades 2.5–6 cm long; 2.5–6 mm wide. Leaf-blade surface smooth, or scaberulous; rough on both sides; glabrous.

INFLORESCENCE Bisexual, or gynodioecious ("male", in this context, indicating the bisexual state). Inflorescence a panicle.

Panicle open; oblong, or ovate; 5–22 cm long. Primary panicle branches spreading, or reflexed; 2–4 -nate. Panicle branches smooth, or scaberulous.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 2–6 fertile florets; with diminished florets at the apex. Spikelets ovate; laterally compressed; 5–9 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes 1 mm long; smooth. Floret callus glabrous.

GLUMES Glumes persistent; similar; shorter than spikelet. Lower glume lanceolate; 1.5–3 mm long; 1 length of upper glume; membranous; 1-keeled; 1–3 -veined. Lower glume lateral veins absent, or distinct. Lower glume apex acute. Upper glume elliptic; 1.5–3 mm long; 0.25–0.75 length of adjacent fertile lemma; membranous; 1-keeled; 3 -veined. Upper glume apex acute.

FLORETS Fertile lemma ovate; 3–6.5 mm long; membranous; keeled; 5 -veined. Lemma midvein eciliate. Lemma surface glabrous. Lemma margins eciliate. Lemma apex acute. Palea 1 length of lemma. Palea keels scabrous. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules 2; membranous. Anthers 3; 1.3–3.6 mm long.

FRUIT Caryopsis with adherent pericarp. Hilum punctiform.

MALE Male spikelets resembling female.

DISTRIBUTION North America: northwest USA and southwest USA.

NOTES Poeae. Soreng 1999.

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