The Jepson Manual: Higher Plants of California

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Names are linked to treatments from the Manual


Key to POLYGONUM

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

  1. 3 outer perianth lobes ± keeled to widely winged, especially in fruit — uncommon aliens (subg. Fallopia)
 
    2. Leaf generally 3–10 cm, ovate-sagittate; vine (sect. Fallopia)
 
      3. Woody perennial herb, perianth bright pink
P. baldschuanicum
      3' Non-woody annual, perianth greenish white
P. convolvulus
    2' Leaf generally 10–30 cm, widely ovate to round; stout per from rhizome; (sect. Reynoutria)
 
      4. Stem generally 1–2 m; leaf blade 10–15 cm, ± round, tip abruptly pointed; perianth ± white
P. cuspidatum
      4' Stem generally 2–3 m; leaf blade 15–30 cm, widely ovate, acuminate; perianth ± green
P. sachalinense
  1' 3 outer perianth lobes not keeled or winged, even in fruit
 
    5. Leaf generally 5–35 cm, petioled (except sometimes P. davisiae), blade generally lanceolate or wider; if annual, stem generally 50–200 cm; filaments thread-like (subg. Persicaria)
 
      6. Stem unbranched, erect; generally subalpine; leaves ± basal, blade generally oblong, strap-shaped; perianth lobes nearly free (sect. Bistorta)
P. bistortoides
      6' Stem branched, generally ± sprawling; lower elevations; leaves cauline, blade rarely oblong; perianth lobes fused to nearly free
 
        7. Leaf widely lanceolate to round
 
          8. Inflorescence head-like, ± spheric, dense; perianth fused ± 1/3 its length (sect. Cephalophilon)
P. capitatum
          8' Inflorescence a panicle or appearing as a small, dense cluster; perianth fused << 1/3 its length (sect. Aconogonon)
 
            9. Inflorescence an open, ± leafless panicle, flowers > 50; stem erect, > 1 m, stout; some leaves > 10 cm
 
              10. Montane native; stem from thick caudex; leaf blade base round to tapered, basal lobes 0
P. phytolaccifolium
              10' North coastal alien; stem from extensive rhizome; leaf blade base tapered, often with 2 small, round lobes
P. polystachyum
            9' Inflorescence a small axillary cluster, flowers 2–25; stem prostrate to decumbent, < 1 m; leaves < 8 cm
 
              11. Petioles < 1 cm; leaf blade generally lanceolate, surfaces ± glabrous to scabrous, yellow-green, margin scabrous, tip acute; flowers 2–5 per axil
P. davisiae
              11' Some petioles > 1 cm; leaf blade generally ovate to round, surfaces ± glabrous to velvety, dark green becoming reddish, tip generally ± round, margin glabrous to soft-hairy; flowers 5–25 per axil
P. newberryi
        7' Leaf ± narrowly lanceolate (except in P. amphibium) — inflorescence spike-like; perianth fused ± 1/3 its length (sect. Persicaria)
 
          12. Perianth gland-dotted; inflorescence ± open, slender; fruit 2–3-angled
 
            13. Perianth margins generally ± red; fruit dark brown, dull, bitter-tasting; annual
P. hydropiper
            13' Perianth margins generally white; fruit black, shiny, not bitter-tasting; perennial herb from rhizome
P. punctatum
          12' Perianth not gland-dotted; inflorescence open or dense; fruit generally 2-angled or ± flat
 
            14. Perianth greenish to light pink; inflorescence spikes 2–6 mm wide
 
              15. Perianth generally light pink, opening, veins at fruiting inconspicuous; fruit 3-angled; perennial herb from extensive rhizome
P. hydropiperoides
              15' Perianth generally greenish, remaining closed, veins at fruiting prominent, forked, recurved; fruit flat, generally indented on both sides; annual
P. lapathifolium
            14' Perianth deep pink; inflorescence spikes 7–20 mm wide
 
              16. Annual; ± terrestrial; stem ± erect (lower nodes sometimes rooting); leaf narrowly lanceolate
 
                17. Stipule (including margin) glabrous; peduncle glandular; fruit ± 3.5 mm, round, nearly flat to indented
P. pensylvanicum
                17' Stipule strigose, margin bristly; peduncle glabrous; fruit ± 2.5 mm, widely ovate, often 3-angled
P. persicaria
              16' Perennial from rhizome; aquatic or on shorelines; stem generally floating or decumbent; leaf widely lanceolate to elliptic
P. amphibium
                18. Stem terrestrial or emergent in flower; leaf blade lanceolate, tip ± acuminate; inflorescence > 4 cm
var. emersum
                18' Stem floating in flower; leaf blade oblong, tip round to acute; inflorescence < 3.5 cm
var. stipulaceum
    5' Leaf generally 1–5 cm, ± sessile, generally linear to lanceolate (to round in P. minimum); annual, subshrub, or shrub, stem generally 3–35 cm; filaments much wider at base (subg. Polygonum)
 
      19. Shrub or subshrub
 
        20. Stem ± erect (gnarled at base), flower branches erect, whip-like; foothills or low mtns
P. bolanderi
        20' Stem prostrate to ascending throughout; coast or high mtns
 
          21. Subshrub; stipule ± 20 mm, persistent; coastal dunes
P. paronychia
          21' Shrub, gnarled; stipule ± 5 mm, ± falling with leaf; high mtns
P. shastense
      19' Annual
 
        22. Stem ± round, obviously and ± regularly 8–16 ribbed (if stem ± angled, ribs obvious between angles); generally alien (sect. Polygonum)
 
          23. Flower clusters scattered, some or all in axils of full-sized leaves; stem prostrate to erect
 
            24. Fruit 3.5–4.5 mm, olive-brown, shiny — uncommon, San Francisco Bay Area salt marshes, possibly native
2 P. marinense
            24' Fruit 2–3 mm (late-season fruit sometimes larger), dark brown, generally ± dull
 
              25. Perianth ± 2.5 mm, exserted from stipule; abundant
P. arenastrum
              25' Perianth ± 2 mm, ± enclosed in stipule; uncommon
P. prolificum
          23' Flower clusters ± restricted to branch tips, in axils of bracts; stem erect
 
            26. All but lowest bracts < flowers or falling early, so inflorescence appears raceme-like and restricted to stem tips; perianth margin pink; fruit < 2 mm, brown, very shiny
P. argyrocoleon
            26' Most bracts > flowers, so inflorescence clusters appear axillary and less restricted to stem tips; perianth green or yellowish (margin rarely pink); fruit > 2 mm, not very shiny
 
              27. Perianth ± green, ± included in stipule; fruit 2–2.5 mm, brown, ± shiny
P. patulum
              27' Perianth generally dark yellowish (especially margin), exserted from stipule; fruit ± 3 mm, dark brown, ± dull
P. ramosissimum
        22' Stem ± sharply angled (especially just below nodes), ribs between angles obscure or 0; native
 
          28. Leaves firm, ± spiny, uniformly linear, joint with stipule obscure; styles free, bases hard, persistent in fruit (sect. Duravia, in part)
 
            29. Plant dense, often cushion-like, 1–7 cm; stipule deeply fringed, segments generally curled
P. parryi
            29' Plant open, 2–40 cm; stipule bristly or shallowly fringed, segments not curled
 
              30. Stipule prominent, silvery, widely lanceolate, ± obscuring leaves, margin fringed
P. bidwelliae
              30' Stipule not at all obscuring leaves, silvery or golden, lanceolate, margin bristly
P. californicum
          28' Leaves soft, not spiny, linear to round (generally lanceolate), joint with stipule obvious; styles fused, falling in fruit as a unit (sect. Monticola)
 
            31. Fruit 1.5–2.5 mm, light brown to nearly black, dull to somewhat shiny (the darkest dull) [subspp. intergrade]
P. polygaloides
              32. Bract margin white; fruit brown to nearly black, generally dull (lanceolate if shiny)
 
                33. Inflorescence ± 7–9 mm wide; bracts ascending to spreading, shorter, rounder upward, white margin wide, generally reflexed; fruit < 2 mm, ovate in outline, nearly black, dull; widespread
subsp. confertiflorum
                33' Inflorescence ± 4–6 mm wide; bracts ± appressed, uniformly lance-elliptic, white margin narrow, generally not reflexed; fruit 2–2.5 mm, lanceolate in outline, brown, generally ± shiny; RARE, Modoc Plateau
subsp. esotericum
              32' Bract margin green; fruit brown, generally ± shiny
 
                34. Bracts lance-elliptic, stiffly appressed; fruit 2–2.5 mm, lanceolate in outline, brown, shiny to ± dull; RARE, Modoc Plateau
subsp. esotericum
                34' Bracts linear-lanceolate, soft, spreading; fruit ± 1.5 mm, ± widely ovate in outline, light brown, ± shiny; widespread
subsp. kelloggii
            31' Fruit 2–5 mm, shiny, black or olive brown
 
              35. Fruit olive-brown; salt marshes, San Francisco Bay Area; uncommon
2 P. marinense
              35' Fruit black; widely distributed; ± common
 
                36. Leaves elliptic to round, persistent, regularly and widely spaced below, barely smaller upward, crowded at stem tips; stem reddish
P. minimum
                36' Lowest leaves linear to oblanceolate or narrowly elliptic, generally falling early, reduced, more widely spaced upward; stem ± green [subspp. intergrade extensively]
P. douglasii
                  37. Perianth 3–5 mm, opening partly or widely; inflorescence open or dense; flowers and fruit generally spreading
 
                    38. Flower clusters scattered; perianth white, opening widely
subsp. majus
                    38' Flower clusters crowded at stem tips; perianth ± pink, opening partly
subsp. spergulariiforme
                  37' Perianth generally 2–3 mm, generally remaining closed; inflorescence ± open; flowers and fruit erect or becoming reflexed
 
                    39. Fruit erect, 2–3 mm; enfolding perianth not stalked at base; leaves uniformly lance-elliptic, gradually smaller upward
subsp. johnstonii
                    39' Fruit reflexed, 2–4 mm; enfolding perianth generally with minute, curved stalk at base; leaves linear to elliptic, abruptly smaller upward
 
                      40. Fruit ± 2 mm; plant funnel-shaped from ascending basal branches; lower leaves ± elliptic, persistent, appearing crowded
subsp. austiniae
                      40' Fruit 3–4 mm; plant ± open, not funnel-shaped; lower leaves linear to oblanceolate, falling early, ± widely spaced
subsp. douglasii


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