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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.


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: America, 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. Fruit indehiscent, short

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

2' Fruit 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 herb; sepals 5–14 mm, widely opening; stalk-like base of fruit short, thick

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

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

1' Fruit dehiscent, generally elongate

5. Fruit 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' Fruit not winged, often angled or tubercled, fertile throughout

8. Fruit 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 herb; hypanthium 30–165 mm; sepals 16–50 mm, tips in bud not free; petals 16–56 mm ..... O. cespitosa

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

8' Fruit not tubercled; petals yellow or white

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

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

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

13' Stem 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 (pl annual or short-lived perennial herb) or 1–9 mm (pl perennial herb) ..... O. deltoides

15. Perennial herb, 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. Fruit 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 High Sierra Nevada ..... O. xylocarpa

19' Petals fading red-purple to orange; fruit not twisted; 1 side of seed with thick, U-shaped area surrounding a groove; Desert ..... 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' Fruit ± cylindric (sometimes slightly wider toward tip); seed 1–2 mm, pitted

21. Stem decumbent to erect; annual or perennial herb (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' Stem 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. Leaf crinkled; seeds and pollen ± 50% sterile ..... O. glazioviana

26' Leaf ± 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


Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, [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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