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 tenerrima

HABIT Perennial; caespitose; clumped densely. Rhizomes absent. Stolons absent. Butt sheaths glabrous. Basal innovations intravaginal. Culms 15–30 cm long; 0.8–0.9 mm diam.; 1 -noded. Leaf-sheaths open for most of their length; with 0.15–0.25 of their length closed; mostly shorter than adjacent culm internode; antrorsely scabrous. Ligule an eciliate membrane; 0.5–1.5(–2.5) mm long; scaberulous on abaxial surface; truncate, or obtuse. Leaf-blades conduplicate; 0.5–1 mm wide. Leaf-blade surface scabrous. Leaf-blade apex abruptly acute; hooded.

INFLORESCENCE Inflorescence a panicle.

Panicle open; pyramidal; 5–15 cm long. Primary panicle branches spreading; 1–2(–5) -nate; 3–8.5 cm long; bearing 3–9 fertile spikelets on each lower branch. Panicle axis with lower internodes 1.5–4.2 cm long. Panicle branches capillary; scabrous.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 3–5 fertile florets; with diminished florets at the apex. Spikelets lanceolate; laterally compressed; compressed slightly; 5–8 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes 1–1.5 mm long; scaberulous. Floret callus glabrous, or pubescent.

GLUMES Glumes persistent; similar; shorter than spikelet. Lower glume lanceolate; 2.5 mm long; 0.7 length of upper glume; membranous; 1-keeled; 3 -veined. Lower glume primary vein scabrous. Lower glume surface scabrous; rough above. Lower glume apex acute. Upper glume lanceolate; 3.5 mm long; 0.8–1.1 length of adjacent fertile lemma; membranous; 1-keeled; 3 -veined. Upper glume primary vein scabrous. Upper glume surface scabrous; rough above. Upper glume apex acute.

FLORETS Fertile lemma elliptic; 3–4.2 mm long; membranous; much thinner above; keeled; lightly keeled; 5 -veined. Lemma midvein pubescent. Lemma lateral veins obscure. Lemma surface puberulous; hairy below. Lemma margins involute; eciliate. Lemma apex obtuse, or acute. Palea keels scabrous. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Anthers 3; 1.6–2.1 mm long.

DISTRIBUTION North America: southwest USA.

NOTES Poeae. Fl N Amer 2007.

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