Poa L.
Poaceae, grass family.
Plants caespitose, or not caespitose; less than 15 cm high, or more than 15 cm high; 5–23–65 cm high. Ground-level or under-ground stems horizontal, or not developed horizontally or vertically underground; rhizomatous (when present); elongate, or compact; 0.5–0.7825–1.2 mm wide. Scales present; grooved; 0.5–1.25–2 mm long; glabrous. Aerial stems erect, or decumbent; circular or oval in cross-section; glabrous. Leaves distributed along the stems (rarely), or mostly basal (usually); alternate; not distinctly distichous; marcescent. Prophylls 0.415–6.788–30 mm long; with smooth veins, or with scabrous veins; with pronounced keels, or lacking pronounced keels. Petioles absent. Sheaths with the margins fused only in the lower part; glabrous; collars collars present. Ligules present; 0.4–1.9–5 mm long; membranous; glabrous, or hairy; linear, or lanceolate, or ovate-oblong, or transversely oblong; apices acuminate, or acute, or obtuse, or truncate; entire, or erose, or lacerate. Blades 5–550 mm long; 0.4–0.8714–1.8 mm wide; appressed to the stem, or spreading from the vertical; folded in bud; linear; with sheath auricles, or without auricles; flat, or folded (with boat shaped tips); with parallel veins; midvein conspicuously larger than the lateral veins, or midvein similar in size to other veins in the leaf; bulliform cells in distinct rows on either side of the midvein, or without bulliform cells in a distinct row on either side of the midvein; adaxial surface glabrous, or scabrous, or hairy. Blades abaxial surface glabrous, or scabrous.
Flowering culm nodes not rooting at the lower nodes; not exposed, or becoming exposed; number visible 0–3. Flag leaf sheaths inflated, or not inflated. Inflorescences paniculate; inflorescence linear, or lanceolate, or ovate; inflorescence 0.3–4–13 cm long; inflorescence 2–25–75 mm wide; inflorescence main axis glabrous, or scabrous. Number of inflorescence branches at lowest node 1–4. Inflorescence primary branches 2–14–50 mm long; glabrous, or scabrous; with appressed secondary branches, or with spreading secondary branches. Spikelets pedicellate; disarticulating above the glumes; laterally compressed; obovate; 3–5.3–7.5 mm long; 1.2–2.8–5.6 mm wide. Florets per spikelet 2–6. First glume 0.7–0.87–1 × the length of the second glume; 0.4–0.6–0.8 × spikelet length; 1.9–3.2–5 mm long; lanceolate, or ovate; glabrous; margins glabrous; veins 1–3; apex acute. Second glume 0.4–0.9 × as long as the spikelet; almost as long as, or longer than, the lowest floret; 2.2–3.7–5 mm long; lanceolate, or ovate, or oblanceolate; glabrous, or with trichomes; veins 3. Rachilla internode 0.6–1.1–1.8 mm long; glabrous. Rachilla not pronounced between the florets; extending beyond the uppermost floret. Callus differentiated, or not differentiated; hairs 1.5–1.75–2 mm long; hairs shorter than the floret. Lemma 2.7–3.9–5.3 mm long; ovate, or lanceolate, or oblanceolate; keeled, or rounded on the back; surface dull; surface hairy; surface with trichomes on and between the veins; veins 5. Lemma apex acute, or rounded, or truncate; entire, or erose; awnless. Palea well developed; 2.3–3.3–4.5 mm long; with scabrous veins, or with hairy veins. Perianth reduced to lodicules. Stamens 3. Anthers 0.6–1.5–2.3 mm long. Carpels syncarpous; 3. Gynoecia superior. Styles 2. Ovules 1. Fruit a caryopsis; indehiscent; 1.4–1.9–2.5 mm long; sessile; dry. Seeds 1.
Chromosome information. 2n = 28–84 (–127).
Ecology and habitat. Substrates, rock (often on sandstone), gravel, sand, silt, clay, till, moss (often of owl perches).
Notes. Restricted generic description combining data for the taxa occurring in the Canadian Arctic Archipelago, using INTKEY.
Cite this publication as: ‘S.G. Aiken, M.J. Dallwitz, L.L.Consaul, R.L. Boles, R. Elven and M.E. LeBlanc. 2001 onwards. Flora of the Canadian Arctic Archipelago. Volume 1. Pteridophytes and Monocotyledons: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 16th March 2001. http://www.mun.ca/biology/delta/arcticf/’. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000), and Aiken, Dallwitz et al. (1999) should also be cited (see References).