| | 1. Annual (rarely biennial); anthers generally 0.2–1.0 mm (–1.8 mm in P. bolanderi); flower generally bisexual |
| |
| | 2. Callus glabrous; upper flowers of spikelet often pistillate (sect. Ochlopoa) |
| |
| | 3. Spikelet axis generally hidden, terminal internode < 1/2 terminal floret length; anthers 0.6–1 mm; widespread |
| P. annua |
| | 3' Spikelet axis visible, terminal internode > 1/2 terminal floret length; anthers 0.2–0.5 mm; especially s California Floristic Province |
| P. infirma |
| | 2' Callus with cobwebby hairs (sect. Diversipoa) |
| |
| | 4. Inflorescence branches appressed; leaf blade abruptly prow-tipped; lemma veins hairy |
| P. bigelovii |
| | 4' Lower inflorescence branches eventually spreading; leaf blade not prow-tipped or lemma glabrous or scabrous |
| |
| | 5. Lemma glabrous or scabrous; leaf blade abruptly prow-tipped; some spikelet internodes generally > 1 mm |
| P. bolanderi |
| | 5' Lemma puberulent; leaf blade tapered, slightly prow-tipped; some spikelet internodes < 1 mm |
| P. howellii |
| | 1' Perennial; anthers often > 1.2 mm; flower sometimes unisexual |
| |
| | 6. Rhizomes or stolons present; anthers 1–4 mm |
| |
| | 7. Stem and nodes distinctly compressed, wiry; leaf sheath open nearly to base; inflorescence branches scabrous (sect. Tichopoa) |
| P. compressa |
| | 7' Stem and nodes little or not compressed or wiry; leaf sheath sometimes not open so far; inflorescence branches sometimes smooth |
| |
| | 8. Lemma glabrous or minutely scabrous; callus long-cobwebby |
| |
| | 9. Leaf blade thin, generally flat; upper surface glabrous or sparsely scabrous; flowers bisexual |
| P. kelloggii |
| | 9' Leaf blade thick, folded and inrolled, upper surface generally finely hairy; flowers generally unisexual (sect. Madropoa) |
| P. piperi |
| | 8' Lemma hairy at least on keel or callus glabrous |
| |
| | 10. Lemma generally < 3.5 mm, lemma and callus smooth, glabrous; stem nodes generally hidden in basal tuft; inflorescence < 8 cm, branches appressed, generally smooth; flowers unisexual (sect. Madropoa) |
| P. atropurpurea |
| | 10' 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 sometimes bisexual |
| |
| | 11. Leaf blade firm, inrolled, upper surface generally densely and finely hairy or scabrous; flowers generally unisexual; coastal sand (sect. Madropoa) |
| |
| | 12. Lemma < 4.5 mm, sparsely hairy; plant < 30 cm; inflorescence ± loose |
| P. confinis |
| | 12' Lemma >> 4.5 mm, glabrous to densely hairy; plant sometimes > 30 cm; inflorescence dense, branches appressed |
| |
| | 13. Upper glume < 7 mm; lowest lemma < 7.5 mm; stem very scabrous or coarsely hairy below inflorescence; s North Coast, Central Coast, n Channel Islands |
| P. douglasii |
| | 13' Upper glume > 7 mm; lowest lemma > 7.5 mm; stem smooth below inflorescence; n&c North Coast |
| P. macrantha |
| | 11' Leaf blade generally not firm or inrolled, upper surface glabrous or sparsely soft-hairy; flowers often bisexual; widespread (if plant otherwise as in 11., then montane) |
| |
| | 14. Sheath of upper stem leaf closed nearly to top, blade > sheath (P. nervosa complex) |
| P. sierrae |
| | 14' Sheath of upper stem leaf open at least 1/4 length, blade < or = sheath |
| |
| | 15. Callus glabrous (rarely short-cobwebby); lemma glabrous or hairy; flowers often pistillate |
| |
| | 16. Lemma generally < 3.5 mm, sometimes glabrous; inflorescence linear in outline, short-branched, interrupted, many-flowered; upper stem-leaf blade > 1/5 sheath length; flowers appearing bisexual but anthers generally sterile; tall leafy-stem plants of moist, low-elevation meadows (see P. secunda subsp. juncifolia) |
| P. pratensis subsp. pratensis × P. secunda |
| | 16' Lemma generally > 3.5 mm; inflorescence lanceolate to ovate in outline (otherwise sometimes as above); upper stem-leaf blade sometimes < 1/6 sheath length; flowers generally pistillate (anthers minute); cespitose or tall plants of well drained soils of slopes of forests |
| |
| | 17. Stem-leaf blades strongly reduced upward, uppermost < 1/8 sheath length; lemma keel and marginal veins obviously hairy; plant densely tufted (sect. Madropoa) |
| 2 P. fendleriana subsp. longiligula |
| | 17' Stem-leaf blades generally longest at middle of stem, uppermost generally > 1/5 sheath length; lemma scabrous or keel and marginal veins sparsely hairy; plant loosely tufted |
| P. wheeleri |
| | 15' Callus long-cobwebby (hairs > 1/2 lemma length); lemma keel and marginal veins hairy, glabrous between veins; flowers bisexual (except P. rhizomata) |
| |
| | 18. Sheath generally open > 3/4 length; stolons generally present; stem sometimes branching above base; lemma sometimes hairy only on keel |
| |
| | 19. First glume generally 3-veined, not arched; lemma obviously hairy on keel and marginal veins (sect. Stenopoa) |
| 2 P. palustris |
| | 19' First glume 1-veined, ± sickle-shaped; lemma sparsely hairy on keel and rarely on marginal veins (sect. Coenopoa) |
| 2 P. trivialis |
| | 18' Sheath open < 3/4 length; plant with obvious rhizomes; stem not branching above base |
| |
| | 20. Plant often forming a dense sod; ligule truncate to rounded; inflorescence densely flowered, branches at lower nodes generally 4 or more (some may be small); lemma generally < 4 mm; flowers rarely pistillate (sect. Poa) |
| P. pratensis subsp. pratensis |
| | 20' Plant not sod-forming; ligule acute; inflorescence sparsely flowered, branches at lower nodes generally 1–2; lemma generally > 4 mm; flowers sometimes pistillate (P. nervosa complex) |
| P. rhizomata |
| | 6' Rhizomes and stolons 0; anthers 0.2–4.5 mm |
| |
| | 21. Most florets replaced by leafy bulblets; stem base bulbous |
| P. bulbosa |
| | 21' Florets not mostly replaced by bulblets; stem base not bulbous |
| |
| | 22. Callus cobwebby; lemma hairy on keel and generally on marginal veins but not between veins |
| |
| | 23. Inflorescence < 10 cm, ± dense; plant densely cespitose |
| |
| | 24. Plant > 20 cm; sheaths open < 1/2 length; flowers pistillate, anthers vestigial |
| 2 P. cusickii subsp. purpurascens |
| | 24' Plant << 20 cm; sheaths open > 3/4 length; flower generally bisexual, anthers 0.8–1.2 mm (sect. Abbreviatae) |
| P. pattersonii |
| | 23' Inflorescence generally > 10 cm or open; plant loosely cespitose |
| |
| | 25. Lower glume generally 3-veined; sheaths open 4/5 length or more (sect. Stenopoa) |
| |
| | 26. Ligule of upper stem leaf truncate, generally < 0.8 mm; generally forest |
| P. nemoralis |
| | 26' Ligule of upper stem leaf acute, generally > 1 mm; generally moist meadow or streamside |
| 2 P. palustris |
| | 25' Lower glume generally 1-veined; sheaths open < 3/4 length |
| |
| | 27. Anthers < 1 mm; inflorescence branches with flowers in top 1/3; high montane to alpine (sect. Oreinos) |
| P. leptocoma subsp. leptocoma |
| | 27' Anthers > 1.3 mm; some inflorescence branches with flowers from midlength; low elevation (sect. Coenopoa) |
| 2 P. trivialis |
| | 22' Callus glabrous or not cobwebby (ring of short callus hairs present in some P. secunda, P. unilateralis); lemma often hairy between veins |
| |
| | 28. 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 (sect. Madropoa) |
| 2 P. fendleriana subsp. longiligula |
| | 28' 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 |
| |
| | 29. Spikelet lanceolate to narrowly ovate in outline, little compressed; lemma weakly keeled; sheath open > 3/4 length; flowers bisexual (sect. Secundae) |
| |
| | 30. Inflorescence branches widely spreading in flower and fruit; plant delicate, spring-active; 500–700 m, often on serpentine |
| P. tenerrima |
| | 30' Inflorescence branches generally ascending to appressed in fruit (if widely spreading in fruit, plant generally more robust, summer-active, of high elevation, not on serpentine) |
| P. secunda |
| | 31. 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; especially Great Basin Floristic Province |
| subsp. juncifolia |
| | 31' Lemma ± evenly short-hairy on keel and sides across base; ligule of sterile shoots and stem generally > 2 mm, acute or acuminate, smooth or sparsely scabrous; leaf blade generally ± soft, soon withering; inflorescence branches appressed or spreading; California |
| subsp. secunda |
| | 29' Spikelet ± ovate in outline, obviously compressed; lemma obviously keeled to base; sheaths sometimes open < 3/4 length; flowers sometimes unisexual |
| |
| | 32. Uppermost sheath open < 1/2 length; lemma > 4.5 mm, sparsely hairy on keel, base, and sometimes marginal veins; flowers pistillate (sect. Madropoa) |
| 2 P. cusickii subsp. purpurascens |
| | 32' Uppermost sheath generally open > 1/2 length; lemma generally < 4.5 mm or glabrous (if hairy, sheath open > 3/4 length, flowers bisexual) |
| |
| | 33. Lemma obviously hairy, < 3.6 mm; subalpine or higher (sect. Stenopoa) |
| P. glauca subsp. rupicola |
| | 33' Lemma often glabrous, length various (if lemma obviously hairy, plant coastal) |
| |
| | 34. Sheath open ± 9/10 length; flowers bisexual; low salty places; coast or w California (sect. Secundae subsect. Halophytae) |
| |
| | 35. Inflorescence branches ascending, very scabrous, with spikelets only in top 1/2; near hot springs, Outer North Coast Ranges, Napa Co. |
| P. napensis |
| | 35' Inflorescence branches appressed, smooth to sparsely scabrous, with spikelets from near base; seabluffs, North Coast, n&c Central Coast |
| P. unilateralis |
| | 34' Sheath open < 9/10 length; flowers sometimes unisexual; generally ± salt-free places; montane or Great Basin Floristic Province |
| |
| | 36. Plant generally < 1 dm; longest anthers 0.2–2 mm; upper glume generally = or > first lemma; lemma sometimes sparsely short-hairy; flowers bisexual (sect. Abbreviatae) |
| |
| | 37. Leaf firm; lemma 3–5 mm; anthers 0.7–2 mm |
| P. keckii |
| | 37' Leaf soft; lemma < 3 mm; anthers 0.2–0.7 mm |
| P. lettermanii |
| | 36' Plant generally 1–7 dm; longest fertile anthers 2–4.5 mm; upper glume generally < first lemma; lemma glabrous; flowers sometimes unisexual (sect. Madropoa subsect. Epiles) |
| |
| | 38. 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; High Sierra Nevada |
| P. stebbinsii |
| | 38' 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 bisexual; more widespread |
| |
| | 39. Plant generally < 30 cm, base often decumbent; leaf blades of sterile stems generally > 1.5 mm wide, arched, their ligules sometimes > 2 mm; upper glume sometimes = first lemma; Klamath Ranges, High Cascade Range, n High Sierra Nevada |
| P. pringlei |
| | 39' Plant 25–70 cm, base rarely decumbent; leaf blades of sterile stems < 1.5 mm wide, erect, their ligules < 2 mm; upper glume obviously < first lemma; widespread, especially Great Basin Floristic Province |
| P. cusickii in part |
| | 40. Basal tuft of leaves sparse; inflorescence branches ± smooth; 1–2 stem nodes exposed; flowers pistillate; moist subalpine |
| subsp. epilis |
| | 40' Basal tuft of leaves dense; inflorescence branches obviously scabrous; 0–1 stem nodes exposed; flowers sometimes staminate (rarely bisexual); moist or dry places |
| |
| | 41. Inflorescence branches slender, longest generally > 17 mm; moist sagebrush to dry montane slopes |
| subsp. cusickii |
| | 41' Inflorescence branches stout, longest generally < 15 mm; dry ± alpine ridges — uncommon in California |
| subsp. pallida
|