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Key to families | Table of families and genera

Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.

 

EPILOBIUM WILLOWHERB

Peter C. Hoch


Annual to subshrub. Leaf: generally opposite proximally (or clustered in axils), generally ± fine-toothed; veins generally obscure. Inflorescence: generally raceme, bracted. Flower: radial or rarely ± bilateral; sepals 4, erect; petals 4, notched; stamens 8, anthers attached at middle, pollen grains generally shed in 4s, cream-yellow; ovary chambers 4, stigma generally club-like, occasionally 4-lobed. Fruit: straight, cylindric to club-like. Seed: generally in 1 row per chamber, generally with white, deciduous hair-tuft.
165 species: worldwide except tropics. (Greek: upon pod, from inferior ovary) [Raven 1976 Ann Missouri Bot Gard 63:326–340; Wagner et al. 2007 Syst Bot Monogr 83:81–95] Incl Boisduvalia, Zauschneria. Most taxa polyploid; many with anthers ± = stigma self-pollinated; many hybrids. Taxa with alternate leaves moved to Chamerion.

Key to Epilobium

1. Annual from taproot; leaves opposite only near base, alternate or clustered distally, ± narrowly lanceolate; proximal stem generally peeling

2. Seed hair-tuft 0

3. Fruit wall tough, generally splitting only on distal 1/3; seeds in 2 rows per chamber; basal branches generally prostrate or decumbent (sect. Epilobiopsis)

4. Fruit 8–12 mm, sharply 4-angled ..... E. cleistogamum

4' Fruit 3.5–8 mm, cylindric ..... E. campestre

3' Fruit wall flexible, splitting to base; seeds in 1 row per chamber or compressed to 1 row per capsule; basal branches ascending or 0 (sect. Boisduvalia)

5. Fruit not beaked, central axis persistent ..... E. densiflorum

5' Fruit beaked, central axis disintegrating

6. Hypanthium 1.5–3 mm, sepals 2–6 mm, petals 3–10 mm; fruit 10–21 mm; seeds in 1 staggered row, 1.8–2.3 mm ..... E. pallidum

6' Hypanthium 0.4–1 mm, sepals 0.7–2 mm, petals 1–3.2 mm; fruit 8–14 mm; seeds in 4 rows, 0.9–1.6 mm ..... E. torreyi

2' Seed hair-tuft present

7. Plant 2–20 dm, ± glandular; hypanthium 1.5–8(16) mm, sepals 1.2–8 mm, petals 2–15(20) mm; seed 1.5–2.7 mm ..... E. brachycarpum

7' Plant 0.5–4.5 dm, nonglandular; hypanthium 0.4–1.5 mm, sepals 1.3–2.5 mm, petals 1.8–5 mm; seed 0.6–1.2 mm

8. Leaves generally folded along midrib, distal clustered; inflorescence dense; petals 1.8–3 mm; seeds 0.6–0.9 mm, papillate ..... E. foliosum

8' Leaves flat, not clustered; inflorescence open; petals 2–5 mm; seeds 0.9–1.2 mm, netted ..... E. minutum

1' Perennial herb to subshrub from caudex, taproot 0; leaves generally opposite up to inflorescence, generally (narrowly) lanceolate to ovate; proximal stem not peeling (except Epilobium rigidum)

9. Hypanthium 17–34 mm; corolla red-orange, ± bilateral (sect. Zauschneria)

10. Matted per 1–2 dm; proximal leaves white-canescent, nonglandular, distal leaves glandular; North Coast, Outer North Coast Ranges ..... E. septentrionale

10' Clumped perennial herb to subshrub 1–12 dm; all leaves alike, generally not white-canescent, glandular or not; widespread California Floristic Province ..... E. canum

11. Leaves linear to lanceolate, generally < 6 mm wide, often clustered; perennial herb to subshrub 2–12 dm ..... subsp. canum

11' Leaves lanceolate to widely ovate, generally > 6 mm wide, not clustered; perennial herb 1–5 dm

12. Leaves widely ovate, prominently toothed, lateral veins conspicuous ..... subsp. garrettii

12' Leaves lanceolate to ovate, ± entire to generally toothed, lateral veins obscure ..... subsp. latifolium

9' Hypanthium generally 0.4–8(16) mm; corolla white or cream-yellow to purple (sect. Epilobium)

13. Stigma 4-lobed; sepals (3)6–15 mm; petals (6)10–24 mm, pink to rose-purple or cream

14. Petals cream-yellow; hair-tufts ± red, persistent; fruit 35–75 mm ..... E. luteum

14' Petals pink to rose-purple; hair-tufts white, deciduous; fruit 8–45 mm

15. Stem 4–10 dm; leaf 30–90 mm, veins ± red, conspicuous; seed 0.9–1.3 mm, ridged ..... E. oreganum

15' Stem < 4 dm; leaf 6–45 mm, veins obscure; seed 1.4–3.4 mm, papillate

16. Petals 6–10 mm; seeds 1–2 per chamber (8 per fruit); fruit 8–16 mm ..... E. nivium

16' Petals 11–24 mm; seeds > 8 per chamber; fruit 20–45 mm

17. Plant 1–4 dm, nonglandular; leaf 20–45 mm, petiole 2–6 mm; hypanthium 1–1.8 mm; seed 2.5–3.4 mm ..... E. rigidum

17' Plant < 2.5 dm, sometimes glandular (especially ovaries); leaf 6–26 mm, petiole 0–3 mm; hypanthium 2–6 mm; seed 1.4–2.1 mm

18. Pedicel in fruit 2–3 mm; leaf 6–20 mm, tip round to obtuse, petiole 0–3 mm; plant ± glaucous ..... E. obcordatum

18' Pedicel in fruit 6–25 mm; leaf 13–26 mm, tip ± acute; petiole 0; plant not glaucous ..... E. siskiyouense

13' Stigma entire, club-like (occasionally cylindric); sepals 1–7.5 mm; petals 1.6–14 mm, white to rose-purple

19. Stem ± erect, with offset rosettes or fleshy underground shoots

20. Leaf veins ± obscure; stem with fleshy bulb-like shoot; seed papillate

21. Pedicel in fruit 10–40 mm; inflorescence ± nodding; leaf 5–45 mm ..... E. hallianum

21' Pedicel in fruit 0–5 mm; inflorescence erect; leaf 10–65 mm ..... E. saximontanum

20' Leaf veins conspicuous; stem with rosette or fleshy shoot; seed ridged ..... E. ciliatum

22. Petals 2–6(9) mm, white to pink; leaf lanceolate, reduced in open inflorescence — basal rosette present ..... subsp. ciliatum

22' Petals 4–14 mm, pink to rose-purple; leaf lanceolate to ovate, little reduced on crowded inflorescence

23. Stem with fleshy shoot; inflorescence long ..... subsp. glandulosum

23' Stem with leafy rosette or shoot; inflorescence flat-topped ..... subsp. watsonii

19' Stem ± ascending, clumped or cespitose; leafy or thread-like stolons sometimes tipped by fleshy bulblets

24. Plant ± glabrous (except scattered inflorescence hairs)

25. Plant 0.8–3(4) dm, matted; stolons thread-like; pedicels 20–65 mm; inflorescence open (bracts << internodes); leaf tip obtuse ..... E. oregonense

25' Plant < 8.5 dm, clumped; stolons short, scaly; pedicels 5–25 mm; inflorescence crowded (bracts ± = internodes); leaf tip subacute ..... E. glaberrimum

26. Stem < 3.5 dm; leaf 10–35 mm, lanceolate to narrowly ovate; fruit 20–55 mm ..... subsp. fastigiatum

26' Stem 2–8.5 dm; leaf 20–70 mm, ± narrowly lanceolate; fruit 45–75 mm ..... subsp. glaberrimum

24' Plant variously hairy, often in decurrent lines on stem

27. Stem densely glandular-hairy; petals 2–3 mm, white ..... E. howellii

27' Stem hairy, nonglandular; petals 2–9 mm, white or pink to rose-purple

28. Stolons thread-like, tipped by fleshy bulblets; leaf ± narrowly lanceolate; seed 1.4–2.2 mm, hair-tuft persistent

29. Leaf densely minutely strigose; inflorescence minutely strigose and glandular ..... E. leptophyllum

29' Leaf minutely strigose only on margins and midrib; inflorescence minutely strigose, nonglandular ..... E. palustre

28' Stolons short, leafy; leaf generally lanceolate or wider; seeds 0.7–2.1 mm, hair-tuft generally deciduous

30. Plant cespitose, < 2.2 dm; leaf 8–28 mm; fruit 17–40 mm

31. Inflorescence ± nodding; pedicel in fruit 10–55 mm; seed 0.7–1.4 mm, netted ..... E. anagallidifolium

31' Inflorescence erect; pedicel in fruit 2–18 mm; seed 1.5–2.1 mm, papillate ..... E. clavatum

30' Plant loosely clumped, 1–5 dm; leaf 15–55 mm; fruit 40–100 mm

32. Pedicel in fruit 5–15 mm; fruit 40–65 mm; seed 0.9–1.2 mm, papillate; petals generally pink to rose-purple ..... E. hornemannii subsp. hornemannii

32' Pedicel in fruit 20–45 mm; fruit 50–100 mm; seed 1.1–1.6 mm, netted; petals generally white ..... E. lactiflorum

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Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
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