Jepson Flora Project: Jepson Interchange    

The Jepson Manual: Higher Plants of California

  • Up-to-date information about California vascular plants is available from the Jepson eFlora.

Names are linked to treatments from the Manual

Key to POA

N.B.: couplets are linked, e.g., 1. is linked to 1'.

  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

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