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Key to PoaView taxon page for Poa
(For a list of species in Poa, use the above link.) Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots. 1. Annual (biennial); anthers generally 0.2–1(1.8) mm; flower generally bisexual  Both male and female reproductive parts occurring and functional in the same plant or structure (e.g., flower, spikelet, inflorescence). 2. Callus glabrous – upper flowers of spikelet  1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts. often pistillate 3. Spikelet axis generally hidden, terminal internode  Segment of an axis (generally a stem) between successive positions (nodes) from which one or more structures (especially leaves, buds, branches, or flowers) arise. < 1/2 terminal floret; anthers 0.6–1 mm; widespread ..... P. annua 3' Spikelet axis visible, terminal internode > 1/2 terminal floret; anthers 0.2–0.5 mm; especially s CA-FP ..... P. infirma 2' Callus with cobwebby hairs 4. Inflorescence branches appressed  Parallel or nearly parallel to and often in contact with surface of origin; used to describe the disposition of hairs, leaves, pedicels, etc. ; leaf  Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets). blade  Expanded portion of a leaf, petal, or other structure, generally flat but sometimes rolled, cylindric, wavy, or cupped. abruptly prow-tipped; lemma  In Poaceae, the lower, generally larger of two sheathing bracts subtending a flower, generally ensheathing the palea (in a sterile lemma, the associated flower and sometimes palea are rudimentary or absent); with the palea and flower, comprising the floret. veins hairy ..... P. bigelovii 4' Lower inflorescence branches eventually spreading  Oriented more or less perpendicularly to the axis of attachment; often, more or less horizontal. ; leaf blade abruptly or slightly prow-tipped; lemma short-hairy or surface glabrous or scabrous 5. Lemma glabrous or scabrous; leaf blade abruptly prow-tipped; some spikelet internodes Segment of an axis (generally a stem) between successive positions (nodes) from which one or more structures (especially leaves, buds, branches, or flowers) arise. > 1 mm ..... P. bolanderi 5' Lemma short-hairy; leaf blade tapered  Gradually (not abruptly) narrower or smaller at base or tip. , slightly prow-tipped; spikelet internodes generally < 1 mm ..... P. howellii 1' Perennial herb; anthers often > 1.2 mm; flowers occasionally unisexual 6. Rhizomes or stolons present; anthers 1–4 mm 7. Stem and nodes  Position on a stem from which one or more structures (especially leaves, buds, branches, or flowers) arise. distinctly compressed  Flattened side-to-side or front-to-back. , keeled, wiry; leaf sheath  A surrounding or partially surrounding, often tubular structure or part of a structure, such as a leaf base in Apiaceae or Poaceae. open nearly to base; inflorescence branches scabrous ..... P. compressa 7' Stem and nodes little or not compressed or wiry; leaf sheath sometimes not open as far; inflorescence branches sometimes smooth 8. Lemma glabrous or minutely scabrous; callus long-cobwebby 9. Sheaths of upper stem leaves open most of their length; leaf blade generally flat; upper surface glabrous or sparsely scabrous; flowers bisexual ..... P. kelloggii 9' Sheaths of upper stem leaves open 1/3–7/10 their length; leaf blade flat, folded, or inrolled, upper surface sometimes finely hairy; flowers generally unisexual 10. Leaf blades thin, soft, generally 0.8–1.5 mm wide, folded, or up to 2.5 mm wide and flat; stem leaves gradually reduced in length upward; lemma (3.2)4.25–5 mm; plants with bisexual flowers or some (rarely all) pistillate or staminate ..... P. diaboli 10' Leaf blades ± thick, firm, generally 1.5–3 mm wide, never flat; stem leaves strongly reduced in length upward; lemma generally 4–7 mm; plants nearly all pistillate- or staminate-flowered ..... P. piperi 8' Lemma hairy at least on keel or callus glabrous 11. Lemma generally < 3.5 mm, lemma and callus smooth, glabrous; stem nodes generally hidden in basal  At or near the base of a plant or plant part. Especially said of leaves clustered near the ground or of a placenta confined to the base of an ovary. tuft; inflorescence < 8 cm, branches appressed, generally smooth; flowers unisexual ..... P. atropurpurea 11' Lemma generally > 3.5 mm or ± scabrous or hairy (if < 4 mm and smooth and glabrous, then some stem nodes well exposed and inflorescence > 8 cm); inflorescence 2–30 cm, branches sometimes ± spreading, sometimes scabrous; flowers bisexual and/or unisexual 12. Leaf blade ± firm, inrolled, upper surface generally densely and finely hairy or scabrous; flowers generally unisexual (except Poa confinis); coastal dunes 13. Lemma <= 4.5 mm, glabrous to sparsely hairy; plant <= 30 cm; inflorescence ± open ..... P. confinis 13' Lemma >> 4.5 mm, glabrous to densely hairy; plant sometimes > 30 cm; inflorescence dense, branches appressed 14. Upper glume  In Poaceae, each of generally two sheathing bracts that are the lowermost parts of a spikelet, subtending one or more florets. < 7 mm; lowest lemma <= 7.5 mm; stem very scabrous or coarsely hairy below inflorescence; s NCo, CCo, n ChI ..... P. douglasii 14' Upper glume > 7 mm; lowest lemma > 7.5 mm; stem smooth below inflorescence; n&c NCo ..... P. macrantha 12' Leaf blade generally not firm or inrolled, upper surface glabrous or sparsely soft-hairy; flowers bisexual and/or unisexual; widespread, generally montane, rarely on coastal dunes 15' Sheath of upper stem-leaf open at least 1/4 length, blade <= sheath 16. Callus glabrous (rarely short-cobwebby); lemma glabrous or hairy; flowers often pistillate 17. Lemma generally < 3.5 mm, sometimes glabrous; inflorescence linear  Elongate, with nearly parallel sides; narrower than elliptic or oblong. in outline, short-branched, interrupted, many-flowered; upper stem-leaf blade > 1/5 sheath length; flowers appearing bisexual but anthers generally sterile; tall leafy-stemmed plants of moist, low-elevation meadows ..... P. pratensis × P. secunda (see Poa secunda subsp. juncifolia) 17' Lemma generally > 3.5 mm; inflorescence lanceolate  Narrowly elongate, widest in the basal half, often tapered to an acute tip. to ovate  Egg-shaped (i.e., widest below the middle) in two dimensions (i.e., in one plane), as a leaf. in outline (otherwise sometimes as above); upper stem-leaf blade sometimes < 1/6 sheath length; flowers generally pistillate (anthers minute); cespitose  Having a densely clumped, tufted, matted, or cushion-like growth form. or tall plants of well drained soils of slopes of forests 18. Stem-leaf blades strongly reduced upward, uppermost < 1/8 sheath length; lemma keel and marginal veins clearly hairy; plant densely cespitose (see 31. for subspecies) ..... P. fendleriana (2) 18' Stem-leaf blades generally longest at middle of stem, uppermost generally > 1/5 sheath length; lemma glabrous to sparsely scabrous or keel and marginal veins sparsely hairy; plant loosely tufted ..... P. wheeleri 16' Callus long-cobwebby (hairs > 1/2 lemma length); lemma keel and marginal veins hairy, glabrous between veins; flowers bisexual (except Poa rhizomata) 19. Sheath generally open > 3/4 length; stolons generally present; stem sometimes branching above base; lemma sometimes hairy only on keel 20. First glume generally 3-veined, not arched; lemma obviously hairy on keel and marginal veins ..... P. palustris (2) 20' First glume 1-veined, ± sickle-shaped; lemma sparsely hairy on keel and rarely on marginal veins ..... P. trivialis (2) 19' Sheath open <= 3/4 length; plant with obvious rhizomes; stem not branching above base 21. Plant often forming a dense sod; ligule  1. In Asteraceae, the 5-lobed, strap- or fan-shaped outer portion of the corolla of a ligulate flower. 2. In most Poaceae and some other grass-like plants, an appendage at the adaxial junction of leaf sheath and blade, generally membranous, sometimes formed of hairs. 3. In Isoetes and, more obscurely, in Selaginella, a membrane that wholly or partially covers a sporangium. truncate  Abruptly (not gradually) narrower or smaller at base or tip, as if cut straight across or nearly so. to rounded; inflorescence densely flowered, branches at lower nodes generally 4+ (some may be small); lemma generally < 4 mm; flowers rarely pistillate ..... P. pratensis subsp. pratensis 21' Plant not sod-forming; ligule acute  Having a short-tapered, sharp tip, the sides convex or straight and converging at less than a right angle. ; inflorescence sparsely flowered, branches at lower nodes generally 1–2; lemma generally > 4 mm; flowers occasionally pistillate ..... P. rhizomata 6' Rhizomes and stolons 0; anthers 0.2–4.5 mm 22. Stem base ± bulbous; most spikelets 1. In Poaceae, one or more florets (each a flower with subtending lemma and generally palea) and generally 2 subtending glumes; in a sterile spikelet, the flower(s) and sometimes palea(s) are rudimentary or absent. 2. In Cyperaceae, the smallest aggregation of flowers (generally more than 2) and associated bracts. producing leafy bulblets  1. Small bulb generally produced at the base of a bulb. 2. Any small, bulb-like structure that propagates a plant, often in a leaf or bract axil. or not ..... P. bulbosa 22' Stem base not bulbous; florets  In Poaceae, a single flower and its immediately subtending bracts (lemma and generally palea, the lemma subtending the palea when the latter is present); in a sterile floret, the flower and sometimes palea are rudimentary or absent. not mostly replaced by bulblets 24' Callus glabrous, with a ring of short hairs, or cobbwebby; if callus cobbwebby then lemma also hairy to some degree 25. Callus ± cobwebby; lemma hairy on keel and generally on marginal veins but not between veins 26. Inflorescence < 10 cm, sparse or dense; plant densely cespitose 26' Inflorescence generally > 10 cm or open; plant loosely cespitose 28. Lower glume generally 3-veined; sheaths open 3/4 length or more 28' Lower glume generally 1-veined; sheaths open to 3/4 length 30' Anthers > 1.3 mm; some inflorescence branches with flowers from mid-length; low elevation ..... P. trivialis (2) 25' Callus glabrous or not cobwebby (ring of short callus hairs present in some Poa secunda, Poa unilateralis); lemma often hairy between veins 31. Lemma obviously hairy at least on keel and marginal veins; flowers unisexual; sheath open ± 1/3 length; uppermost stem-leaf blade firm, often highly reduced; callus glabrous ..... P. fendleriana (2) 31' Lemma often glabrous (if obviously hairy on keel and marginal veins or between, then flowers bisexual, sheaths open > 3/4 or < 1/2 length; uppermost stem-leaf blade often thin and withering or not highly reduced); callus sometimes with a crown of short hairs 33. Spikelet lanceolate to narrowly ovate in outline, little compressed; lemma weakly keeled; sheath open > 3/4 length; flowers bisexual 34. Inflorescence branches widely spreading in flower and fruit, generally densely scabrous; ligule 0.5–1.5(2.5) mm, truncate to obtuse  Having a short-tapered, blunt tip or base, the sides convex or straight and converging at more than a right angle. (rarely acute), scabrous; plant delicate, spring-active; often on serpentine ..... P. tenerrima 34' Inflorescence branches generally ascending  Curving or angling upward from base, or about 30-60 degrees less than vertical or away from axis of attachment. to appressed in fruit (generally spreading only in flower), ± scabrous; plant generally more robust, or summer-active, of high elevation, or delicate with branches ± smooth and ligules longer and ± smooth; on various substrates ..... P. secunda 35. Lemma glabrous (sometimes scabrous, rarely sparsely short-hairy); ligule of sterile shoots and often stem < 2 mm, ± truncate, scabrous; leaf blade ± firm, retaining shape; inflorescence branches appressed ..... subsp. juncifolia 35' Lemma ± evenly short-hairy on keel and sides across base; ligule of sterile shoots and stem generally > 2 mm, acute or acuminate  Having a long-tapered, sharp tip, the sides concave. , smooth or sparsely scabrous; leaf blade generally ± soft, soon withering; inflorescence branches appressed or spreading ..... subsp. secunda 33' Spikelet ± ovate in outline, obviously compressed; lemma obviously keeled to base; sheaths sometimes open < 3/4 length; flowers sometimes unisexual 36' Uppermost sheath generally open > 1/2 length; lemma generally < 4.5 mm or glabrous (if hairy, sheath open > 3/4 length, flowers bisexual) 37' Lemma often glabrous, length various (if lemma obviously hairy, plant coastal) 38. Sheath open ± 9/10 length; flowers bisexual; low salty places; coast or w CA 39. Inflorescence branches ascending, very scabrous, with spikelets only in top 1/2; near hot springs, NCoRO, Napa Co. ..... P. napensis 38' Sheath open < 9/10 length; flowers sometimes unisexual; generally ± salt-free places; montane or GB 40. Plant generally < 1 dm; longest anthers 0.2–2 mm; upper glume generally >= first lemma; lemma sometimes sparsely short-hairy; flowers bisexual 40' Plant generally 1–7 dm; longest fertile anthers 2–4.5 mm; upper glume generally < first lemma; lemma glabrous; flowers sometimes unisexual 42. Ligule of uppermost leaf of sterile stems 2.5–6 mm, acute, smooth; lemma <= 5.5 mm; lowest true leaves lacking blades; flowers bisexual or pistillate (rarely staminate); SNH ..... P. stebbinsii 42' Ligule of uppermost leaf of sterile stems generally < 2 mm (if 2–3 mm, lemma > 5.5 mm), truncate to obtuse, scabrous; lowest true leaves sometimes with blades; all flowers generally unisexual; more widespread 43. Plant generally < 30 cm, base often decumbent  lying mostly flat on the ground but with tips curving up. ; leaf blades of sterile stems generally > 1.5 mm wide, arched, their ligules sometimes > 2 mm; upper glume sometimes = first lemma; KR, CaRH, n SNH ..... P. pringlei 43' Plant 25–70 cm, base rarely decumbent; leaf blades of sterile stems < 1.5 mm wide, erect  Upright; vertically oriented. , their ligules < 2 mm; upper glume obviously < first lemma; widespread, especially GB ..... P. cusickii (in part) 44. Basal tuft of leaves sparse; inflorescence branches ± smooth; 1–2 stem nodes exposed; flowers pistillate ..... subsp. epilis 44' Basal tuft of leaves dense; inflorescence branches obviously scabrous; 0–1 stem nodes exposed; flowers sometimes staminate (rarely bisexual) 45. Inflorescence branches slender, longest generally > 17 mm; moist sagebrush to dry montane slopes ..... subsp. cusickii 45' Inflorescence branches stout, longest generally < 15 mm; dry ± alpine ridges – uncommon in California ..... subsp. pallida
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Citation for the whole project: Jepson Flora Project (eds.) . Jepson eFlora, https://ucjeps.berkeley.edu/eflora/ [accessed on ]
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