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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.

 

RANUNCULUS BUTTERCUP

Alan T. Whittemore


Annual, perennial herb, occasionally from stolons or caudices, terrestrial or aquatic; roots generally fibrous. Stem: prostrate to erect. Leaf: basal, cauline, or both, alternate, generally reduced upward; petiole base flat, stipule-like or not; basal, proximal cauline petioles generally long; blades simple to dissected or compound, entire to toothed. Inflorescence: cyme, axillary or terminal, 1–few-flowered. Flower: sepals 3–5(6), generally early-deciduous, generally green to yellow or purple; petals 0–17[(150)], shiny, generally yellow, occasionally white or purple, nectaries near base, pocket-like or with flap-like scale; anthers yellow; pistils generally many. Fruit: achene, compressed or not, ± spheric, disk-like (width 3–15 × depth), or lenticular (width 1–2 × depth), beaked.
± 300 species: worldwide except lowland tropics; some ornamental. (Latin: small frog, from wet habitats)
Unabridged etymology: (Latin: diminutive of Rana, frog, from wet habitats)

Key to Ranunculus

1. Leaves generally simple, unlobed

2. Petals 1–3, 1.5–2.5 mm, ± = sepals; fruit body 1–1.8 mm, beak 0 or < 0.1 mm

3. Bracts elliptic to ovate; sepals 3 ..... R. bonariensis var. trisepalus

3' Bracts linear to lanceolate or oblanceolate; sepals 4–5 ..... R. pusillus

2' Petals 4–12, 2–14 mm, generally >= sepals; fruit body 1–4.2 mm, beak 0.1–1.4 mm.

4. Stems erect, decumbent, or prostrate, generally rooting at nodes

5. Fruit wall papery, longitudinally ribbed; leaf tip rounded, margin crenate to crenate-serrate ..... R. cymbalaria

5' Fruit wall thick, smooth (occasionally hairy); leaf tip acute, acuminate, or rounded-obtuse to thread-like, margin entire or finely toothed

6. Lower cauline leaf blade lanceolate to oblanceolate or linear ..... R. flammula

7. Stems erect to prostrate; sepals 3–4 mm; petals 5–7 mm, 3–4 mm wide ..... var. flammula

7' Stems prostrate, occasionally ascending; sepals 2–3 mm; petals 3–5 mm, 2–3 mm wide ..... var. ovalis

6' Lower cauline leaf blade generally ovate

8. Root fusiform-thickened proximally; Klamath Ranges ..... R. gormanii

8' Root not thickened; East of Sierra Nevada ..... R. hydrocharoides

4' Stems erect or ascending, not rooting at nodes

9. Sepals white or pale yellow, 6–13 mm, 3–6 mm wide; petals 8–12, 2–4 mm, ± green; basal leaves shallowly lobed, cauline leaves 0–2, scale-like, unlobed ..... R. hystriculus

9' Sepals green, 2–6 mm, 1–4 mm wide; petals 4–6(8), 4–14 mm, yellow; basal leaves unlobed, not differentiated from cauline, cauline unlobed, at least lower large, petioled, not scale-like

10. Basal leaf bases cordate to obtuse ..... R. populago

10' Basal leaf bases acute ..... R. alismifolius

11. Leaf blade ovate or elliptic ..... var. alismellus

11' Leaf blade lanceolate

12. Leaves minutely serrate; stem 3.5–8 mm diam ..... var. alismifolius

12' Leaves entire; stem 1–3 mm diam

13. Petals 6–8 mm; root not or ± fusiform-thickened proximally ..... var. hartwegii

13' Petals 10–14 mm; root generally fusiform-thickened proximally ..... var. lemmonii

1' Leaves deeply lobed or compound (except basal leaves of Ranunculus glaberrimus)

14. Stems prostrate to decumbent or creeping, rooting at nodes, or floating in water, rootless.

15. Leaves 1-ternate; meadows, road banks, disturbed places, edges of marshes, streams ..... R. repens

15' Leaves lobed, parted, or dissected into thread-like segments; aquatic or on drying mud

16. Petals yellow; fruit smooth ..... R. flabellaris

16' Petals white, or only claws yellow; fruit strongly wrinkled

17. Receptacle glabrous; style 1–1.5 mm; achenes 2–6, bodies 2–2.4 mm; submersed leaves generally 2–3-dissected; annual ..... R. lobbii

17' Receptacle bristly; style 0.2–1.2 mm; achenes 15–many, bodies 1–2 mm; submersed leaves generally 3–6-dissected; perennial herb ..... R. aquatilis

18. Floating leaves 0 or reniform, 3-parted, segments obovate or fan-shaped, submersed leaves dissected into thread-like segments ..... var. aquatilis

18' Floating and submersed leaves dissected into thread-like segments ..... var. diffusus

14' Stems erect to ascending or decumbent (prostrate), generally not rooting at nodes, not floating, occasionally decumbent, rooting only at lowest nodes

19. Style 0; fruit margins thick, corky; plant emergent aquatic, occasionally on mud ..... R. sceleratus

20. Fruit faces smooth; leaves parted, generally deeply, segments lobed or parted, deeply crenate or again lobed ..... var. multifidus

20' Fruit faces finely transversely wrinkled; leaves lobed or parted, segments undivided or lobed, crenate ..... var. sceleratus

19' Style present; fruit margins ridged to narrowly winged, or differentiated margins not evident; plant on wet or dry soil

21. Fruit wall papery, inflated; petals ± pink-white ..... R. andersonii

21' Fruit wall thick, not inflated; petals yellow, occasionally ± purple abaxially

22. Cauline leaves 0; fruit beak >> body ..... R. testiculatus

22' Cauline leaves well developed; fruit beak generally < body

23. Fruit lenticular, width 1–2 × depth; stem glabrous

24. Basal leaves entire or with 3 wide, rounded teeth distally ..... R. glaberrimus

25. Basal leaves elliptic to very narrowly elliptic, entire (or with 3 wide, rounded teeth distally); bract lobes 3, middle >> lateral ..... var. ellipticus

25' Basal leaves ovate to obovate or reniform, with 3 wide, rounded, teeth distally (or entire); bract lobes 3, equal ..... var. glaberrimus

24' Basal leaves 3–9-lobed or 3-parted ..... R. eschscholtzii

26. Ultimate leaf segments acute to acuminate ..... var. suksdorfii

26' Ultimate leaf segments rounded, obtuse, or widely rounded-acute

27. Persistent leaf bases on caudex 0–few; basal leaves 3-parted ..... var. eschscholtzii

27' Persistent leaf bases on caudex many; basal leaves shallowly 5–9-lobed or occasionally 3-parted ..... var. oxynotus

23' Fruit disk-like, width 3–15 × depth; stem hairy or glabrous

28. Fruit faces papillate or spiny

29. Petals 1–2 mm; fruit faces papillate, each papilla tipped with hooked bristle

30. Fruit ornamented on faces, margins, beaks lanceolate ..... R. hebecarpus

30' Fruit ornamented on faces, not margins, beaks deltate ..... R. parviflorus

29' Petals 4–10 mm; fruit faces generally papillate or spiny, hooked bristles 0

31. Fruit spiny ..... R. arvensis

31' Fruit papillate or tubercled (smooth)

32. Basal leaves simple; fruit beak 2–2.5 mm ..... R. muricatus

32' Basal leaves 1–2 ternate; fruit beak 0.3–0.7 mm ..... R. sardous (2)

32a. Petals 7–10 mm; fruit beak 0.4–0.7 mm ..... R. sardous

32a' Petals 4–5 mm; fruit beak ± 0.3 mm ..... [R. trilobus]

28' Fruit faces smooth

33. Petals 2–6 mm, ± = sepals

34. Petals 4–6 mm; basal leaves 1-ternate ..... R. macounii

34' Petals 2–4(6) mm; basal leaves 3-parted, occasionally 1-ternate ..... R. uncinatus

33' Petals 5–26 mm, if 5–6 mm then >> sepals

35. Sepals spreading ..... [R. acris]

35' Sepals reflexed 1–3 mm from base

36. Petals 9–17

37. Fruit body 3.4–4.2 mm, beak deltate ..... R. canus var. ludovicianus

37' Fruit body 1.8–3.2 mm, beak lanceolate ..... R. californicus

38. Stem erect to decumbent, glabrous or spreading-hairy; ultimate segments of basal leaves acute to rounded-acute ..... var. californicus

38' Stem prostrate, strigose; ultimate segments of basal leaves rounded to obtuse ..... var. cuneatus

36' Petals 5–7

39. Fruit beak straight

40. Receptacle glabrous ..... R. occidentalis (in part) (2)

41. Ultimate leaf segments lanceolate to oblanceolate ..... var. dissectus

41' Ultimate leaf segments narrowly elliptic ..... var. howellii

40' Receptacle bristly ..... R. orthorhynchus

42. Basal leaves simple to compound, leaflets 0 or 3, undivided, crenate; petals notched ..... var. bloomeri

42' Basal leaves compound, leaflets 3–5, lobed or parted, entire, dentate, or dentate-lobed; petals rounded

43. Fruit aggregate hemispheric, occasionally spheric, 5–7 mm; petals generally red abaxially ..... var. orthorhynchus

43' Fruit aggregate spheric or ovoid, 8–13 mm; petals yellow abaxially ..... var. platyphyllus

39' Fruit beak curved or tip hooked

44. Base of stem bulbous, corm-like ..... [R. bulbosus]

44' Base of stem not enlarged

45. Receptacle long-hairy; fruit wall coarsely papillate (smooth), beak 0.4–0.7 mm ..... R. sardous (2)

45' Receptacle glabrous; fruit wall generally smooth, beak 0.2–1.4 mm

46. Fruit beak deltate, body 3.4–4.4 mm ..... R. canus var. canus

46' Fruit beak lanceolate, body 2.6–3.6(4) mm ..... R. occidentalis (in part) (2)

47. Petals 3–6 mm wide; 0–1500 m ..... var. occidentalis

47' Petals 1.5–2.5 mm wide; 1300–2500 m ..... var. ultramontanus

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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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