Jepson eFlora
Key to families | Table of families and genera

Key to Oenothera

View taxon page for Oenothera

Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots.

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

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

20. Stem decumbent to erect; annual or perennial herb (except Oenothera stricta, Oenothera pubescens biennial); flowers few, in distal axils

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

21' Bud nodding or curved upward; petal base unspotted

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

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

20' Stem erect; biennial; flowers in generally dense spikes; seeds angled, irregularly pitted

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

23' Hypanthium 20–55 mm

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

25. Leaf crinkled; seeds and pollen ± 50% sterile ..... O. glazioviana

25' Leaf ± flat, ± not crinkled; seeds and pollen ± all fertile ..... O. elata

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

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

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

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

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

28. 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

28' 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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