The Jepson Herbarium
		University of California, Berkeley

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Annual to perennial herb, generally from taproot, occasionally rhizomed.
Leaf: basal or cauline, alternate, generally pinnately toothed to lobed, generally sessile.
Inflorescence: spike, raceme-like, or flowers in axils of distal, reduced leaves.
Flower: radial or (sect. Gaura) bilateral, generally opening at dusk; sepals 4, reflexed in flower (sometimes 2–3 remaining adherent); petals 4, yellow, white, rose, or ± purple, generally fading ± orange to ± purple, tip notched or toothed; stamens 8, filaments sometimes (sect. Gaura) with paired teeth at base, anthers attached at middle; ovary chambers 4, stigma generally deeply lobed, generally > anthers and cross-pollinated (or ± = anthers and self-pollinated).
Fruit: generally dehiscent, cylindric to ovoid or obovoid, cylindric to 4-winged or -angled, straight to curved, generally sessile (base sometimes seedless, stalk-like).
Seed: in generally 2(1–3) rows per chamber, or clustered or reduced to 1–4 per fruit.
145 species: Am, some widely naturalized. (Greek: wine-scented) [Wagner et al. 2007 Syst Bot Monogr 83:1–240]
Unabridged references: [Raven & Gregory 1972 Mem Torrey Bot Club 23:1–96; Dietrich & Wagner 1988 Syst Bot Monogr 24:1–91]
Unabridged note: Many species self-pollinated; some of these have chromosome peculiarities (ring of 14 in meiosis) and ± 50% pollen fertility; they yield genetically identical offspring.

Key to Oenothera

1. Fr indehiscent, short

2. Fr ± linear; stalk-like base 2–8 mm, slender ..... O. sinuosa

2' Fr fusiform to ovoid; stalk-like base 0–3 mm, thick if present

3. Annual; sepals 2–3.5 mm, barely opening; stalk-like base of fruit 0 ..... O. curtiflora

3' Perennial; sepals 5–14 mm, widely opening; stalk-like base of fruit short, thick

4. Fr base > 1/2 diam of widest part, fruit becoming wider ± gradually; caudex woody, branched below ground ..... O. suffrutescens

4' Fr base ± 1/4 diam of widest part, fruit with a conspicuous, abrupt bulge near middle; rhizomed ..... O. xenogaura

1' Fr dehiscent, generally elongate

5. Fr winged, angled or ribbed, basal part sterile

6. Petals yellow; fruit winged in distal 2/3, not narrower toward base ..... O. flava

6' Petals white, rose, or rose-purple; basal part of fruit narrower, sterile; seeds clustered

7. Hypanthium 4–8 mm; petals 5–10 mm; fruit base tapered ..... [O. rosea]

7' Hypanthium 10–23 mm; petals 25–40 mm; fruit base cylindric ..... O. speciosa

5' Fr not winged, often angled or tubercled, fertile throughout

8. Fr tubercled; petals white

9. Annual; hypanthium 20–37(47) mm; sepals 4.5–12 mm; petals 6.5–20(25) mm ..... O. cavernae

9' Perennial; hypanthium 30–165 mm; sepals 16–50 mm, tips in bud not free; petals 16–56 mm ..... O. cespitosa

10. Fr 10–34 mm, lanceolate to elliptic-ovate, generally S-shaped, stalk-like base 0–1 mm; petals fading rose to purple; margin of seed-cavity lobed ..... subsp. crinita

10' Fr 25–68 mm, cylindric, ± straight, stalk-like base 0–55 mm; petals fading lavender to pink; margin of seed-cavity entire ..... subsp. marginata

8' Fr not tubercled; petals yellow or white

11. Petals white; stem peeling; bud nodding; seeds in 1 row per chamber

12. Perennial; new shoots generally from lateral roots; free sepal tips in bud 0 or < 1 mm ..... O. californica

13. St hairs dense, short, appressed and long, spreading, wavy; roots fleshy; new rosettes at stem tips ..... subsp. eurekensis

13' St hairs 0 (to dense, short, appressed and long, spreading); roots not fleshy; new rosettes not forming at stem tips

14. Cauline leaves generally ± pinnately lobed; plant ± gray-green ..... subsp. avita

14' Cauline leaves ± entire to deeply wavy-dentate; plant green to slightly ± gray ..... subsp. californica

12' Annual or perennial herb; new shoots from lateral roots 0; free sepal tips in bud 0–1.2 mm (plant annual or short-lived perennial herb) or 1–9 mm (plant per) ..... O. deltoides

15. Perennial, gray-green; free sepal tips in bud 1–9 mm ..... subsp. howellii

15' Annual or short-lived perennial herb, green; free sepal tips in bud 0–1 mm

16. Distal leaves pinnately lobed; stem generally < 1 dm; petals 15–25(30) mm ..... subsp. piperi

16' Distal leaves ± entire to ± dentate, rarely pinnately lobed; stem generally 2–10 dm; petals 15–43 mm

17. Spreading hairs ± 2 mm distally; fruit base 3–5 mm wide ..... subsp. cognata

17' Spreading hairs 1–1.5 mm distally; fruit base 2–3 mm wide ..... subsp. deltoides

11' Petals yellow; stem generally not peeling; buds generally erect(nodding in Oenothera pubescens); seeds generally in 2 rows per chamber

18. Fr lanceolate to ovate; seed 2.4–3.5 mm, ± wrinkled

19. Petals fading deep salmon-red; fruit twisted; 1 side of seed with 2 small ridges; c&s SNH ..... O. xylocarpa

19' Petals fading red-purple to orange; fruit not twisted; 1 side of seed with thick, U-shaped area surrounding a groove; D ..... O. primiveris

20. Petals (22)29–40 mm; leaf gray-green ..... subsp. bufonis

20' Petals 6–25(28) mm; leaf generally green ..... subsp. primiveris

18' Fr ± cylindric (sometimes slightly wider toward tip); seed 1–2 mm, pitted

21. St decumbent to erect; annual or per (except Oenothera stricta, Oenothera pubescens biennial); flowers few, in distal axils

22. Bud erect; petal base generally with a red spot ..... [O. stricta subsp. stricta]

22' Bud nodding or curved upward; petal base unspotted

23. Bud curved upward; sepal free tips in bud 0.3–3 mm ..... O. laciniata

23' Bud nodding; sepal free tips in bud 0.1–1 mm ..... O. pubescens

21' St erect; biennial; flowers in generally dense spikes; seeds angled, irregularly pitted

24. Hypanthium 60–135 mm ..... O. longissima

24' Hypanthium 20–55 mm

25. Petals 25–52 mm; stigma well exceeding anthers; pollen ± all fertile or ± 50% sterile (sterile grains small and shriveled at 10×)

26. Lf crinkled; seeds and pollen ± 50% sterile ..... O. glazioviana

26' Lf ± flat, ± not crinkled; seeds and pollen ± all fertile ..... O. elata

27. Sepals green or red-flushed; red blister-like hair bases on sepals ± 0; anthers 8–15 mm ..... subsp. hirsutissima

27' Sepals red-flushed; red blister-like hair bases on sepals conspicuous; anthers 12–23 mm ..... subsp. hookeri

25' Petals 7–25(30) mm; stigma ± not exceeding anthers; pollen ± 50% sterile

28. Petals 13–23 mm, generally < sepals; generally coastal ..... O. wolfii

28' Petals 7–25(30) mm, ± = sepals; generally not near coast

29. Spike dense (internodes in fruit < fruit); longest hairs generally without red blister-like bases; petals 10–25(30) mm; sepals green or ± yellow (± red) ..... O. biennis

29' Spike ± open (internodes in fruit generally > fruit); longest hairs generally with red blister-like bases; petals 7–20 mm; sepals often marked ± red ..... O. villosa subsp. strigosa

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Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html [accessed on month, day, year]
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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