Jepson eFlora: Key page
Vascular Plants of California
Key to families | Table of families and genera

Key to Oenothera

View taxon page for Oenothera

(For a list of species in Oenothera, use the above link.)

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

1. Fruit , short

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

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

3. Annualsepals 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;  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 , generally elongate

5. Fruit winged, angled or ribbed 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  ..... [O. rosea]

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

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

8. Fruit tubercled; petals white

9. Annual;  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  not free; petals 16–56 mm ..... O. cespitosa

10. Fruit 10–34 mm,  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  ..... 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. avita

13. Stem hairs dense, short,  and long, , wavy; roots fleshy; new  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  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 ± , 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;  generally erect(nodding in Oenothera pubescens); seeds generally in 2 rows per chamber

18. Fruit lanceolate to 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

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

20. Stem  to ; 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 antherspollen ± 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


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