Ranunculus
Ranunculus sect. Ranunculus
buttercup, crowfoot, renoncule, water-buttercup
basal, sometimes also nodal, sometimes tuberous.
erect to decumbent, sometimes stoloniferous, sometimes bulbous-based, without bulbils.
blade reniform to linear, margins entire, crenate, or toothed.
basal and cauline, petiolate;
basal deeply parted or compound (except sometimes in R. orthorhynchus var. bloomeri), blades with segments lobed or parted, margins toothed;
cauline deeply parted or compound, similar to basal or with shorter petioles and/or blades with narrower segments (rarely poorly developed in R. fascicularis).
terminal or axillary, 2-50-flowered cymes to 25 cm or solitary flowers;
bracts present or absent, small or large and leaflike, not forming involucre.
1-50-flowered cymes.
bisexual, radially symmetric;
sepals sometimes persistent in fruit, 3-5(-6), green or sometimes purple, yellow, or white, plane (base saccate in R. ficaria), oblong to elliptic, ovate, or lanceolate, 1-15 mm;
petals 0-22(-150), distinct, yellow, rarely white, red, or green, plane, linear to orbiculate, 1-26 mm;
nectary present, usually covered by scale;
stamens (5-)10-many;
filaments filiform;
staminodes absent between stamens and pistils;
pistils 4-250, simple;
ovule 1 per ovary;
style present or absent.
pedicellate;
sepals deciduous soon after anthesis, 5 (sometimes 6 in R. occidentalis var. hexasepalus);
petals always present, yellow, sometimes abaxially reddish, rarely poorly developed;
nectary scale attached basally, free from petal for at least 1/2 its length, forming flap covering nectary (or sometimes attached on 3 sides, forming pocket in R. recurvatus), glabrous, free margin entire;
style present.
achenes, rarely utricles, aggregate, sessile, discoid, lenticular, globose, obovoid, or cylindric, sides sometimes veined;
beak present or absent, terminal, straight or curved, 0-4.5 mm.
achenes, 1-locular;
achene body discoid, strongly flattened, 3-15 times as wide as thick, not prolonged beyond seed;
wall thick, not ornamented;
margin low or high narrow ridge or wing;
beak much shorter than achene body.
= 7, 8.
Ranunculus
Ranunculus sect. Ranunculus
Species about 300 (76 in the flora).
Most Ranunculus species are poisonous to stock; when abundant, they may be troublesome to ranchers. A few species with acrid juice were formerly used as vesicatories. The genus is badly in need of biosystematic work. Apomixis and interspecific hybridization occur in several Old World groups of buttercups; some of the taxonomic complexity of the New World species probably results from these processes.
Considerable disagreement exists among authors on the proper generic and infrageneric classification of Ranunculus. Most of the subgenera accepted here have been treated as separate genera at one time or another. All recent studies have been based on local or continental floras, however, and classifications proposed for one region may not work for the plants of other regions. Like most North American workers, I have followed the generic and infrageneric classification of L. D. Benson (1948), who gave by far the most thorough and best documented study of the problem. The genus and its subdivisions should be studied on a worldwide basis.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species ca. 100 (19 in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. All leaves simple and unlobed. | → 2 |
1. Some or all leaves simple and lobed, or compound. | → 9 |
2. Cauline leaves absent or scalelike; sepals deciduous or persistent. | → 3 |
2. Cauline leaves present, well developed; sepals deciduous. | → 5 |
3. Petals 5; achene beak 0.1-0.2 mm; plants stoloniferous, without caudices. | Halodes (Ranunculus cymbalaria) |
3. Petals 8-18; achene beak 0.8-1.4 mm; plants not stoloniferous, stems erect from short caudices. | → 4 |
4. Leaf blades undivided, margins entire or serrulate; sepals persistent in fruit; petals 7-12 mm. | Oxygraphis (Ranunculus kamtschaticus) |
4. Leaf blades shallowly lobed, margins crenate; sepals deciduous; petals 2-4 mm | Pseudaphanostemma (Ranunculus hystriculus) |
5. Tuberous roots present; flowers yellow; sepals 3. | Ficaria (Ranunculus ficaria) |
5. Tuberous roots absent (roots thickened proximally in some 5-sepaled species of sect. Flammula); flowers yellow, white, or pink. | → 6 |
6. Achenes 4.2-5.2 mm, achene body prolonged beyond seed as corky distal appendage; sepals 3, 6-10 mm; petals white to pink. | Pallasiantha (Ranunculus pallasii) |
6. Achenes 0.8-2.8 mm, achene body not prolonged beyond seed; sepals (3-)4-5, 1.5-12 mm; petals yellow. | → 7 |
7. Sepals covered with dense brown pubescence; distal leaves and bracts apically 3-crenate or shallowly 3-lobed, otherwise undivided. | Epirotes (Ranunculus macauleyi) |
7. Sepals glabrous or with colorless hairs; distal leaves simple and undivided. | → 8 |
8. Achene wall papery, longitudinally ribbed; leaf apex broadly rounded to truncate, margins crenate. | Halodes (Ranunculus cymbalaria) |
8. Achene wall thick, not ornamented, smooth (sometimes pubescent); leaf apex acuminate to rounded-obtuse, margins entire or finely toothed. | sect. Flammula |
9. Leafy stems creeping and rooting at nodes or floating in water, then rootless. | → 10 |
9. Leafy stems erect or if decumbent rooting only at base, never floating. | → 14 |
10. Leaves 3-foliolate. | sect. Ranunculus |
10. Leaves simple, lobed to filiform-dissected or occasionally undivided. | → 11 |
11. Achene body prolonged beyond seed as corky distal appendage; sepals 3, petals 5-11. | → 12 |
11. Achene body not prolonged beyond seed; either sepals 5 or sepals 3-4 and petals also 3-4. | → 13 |
12. Leaf blade as wide as long, ternately divided to base. | Coptidium (Ranunculus lapponicus) |
12. Leaf blade much longer than wide, unlobed or lobed. | Pallasiantha (Ranunculus pallasii) |
13. Petals white or white with yellow claws; achenes with strong coarse wrinkles. | subg. Batrachium |
13. Petals yellow; achenes smooth (faintly wrinkled in R. sceleratus var. sceleratus). | sect. Hecatonia |
14. Petals pure red, or white when immature; fruits winged achenes or utricles. | subg. Crymodes |
14. Petals yellow, rarely also with some red pigmentation abaxially, or greenish yellow; fruits achenes, rarely winged. | → 15 |
15. Cauline leaves absent or scalelike, tuberous roots absent; leaves sometimes deeply parted or dissected, never compound. | → 16 |
15. Cauline leaves present, simple, lobed or dissected, or compound (rarely reduced to scales in R. fascicularis with tuberous roots and 3-5-foliolate leaves). | → 18 |
16. Plants villous; sepals 3-6 × 1-2 mm, persistent in fruit; fruit wall firm, smooth, beak much longer than achene body. | Ceratocephala (Ranunculus testiculatus) |
16. Plants glabrous; sepals 6-13 × 3-7 mm, deciduous in fruit; fruit wall thin, veined, beak much shorter than achene body. | → 17 |
17. Leaves shallowly 5-7-lobed; petals inconspicuous, 2-4 mm. | Pseudaphanostemma (Ranunculus hystriculus) |
17. Leaves 3-5-parted; petals showy, 8-12 mm. | Arcteranthis (Ranunculus cooleyae) |
18. Style absent, stigma sessile; achene margins thick and corky; emergent aquatic, sometimes also found on very wet soil. | Hecatonia (Ranunculus sceleratus) |
18. Style present; achene margins not corky; in various habitats but rarely aquatic. | → 19 |
19. Achene wall thin, longitudinally striate; scale of nectary reduced to low ridge, not covering nectary. | Cyrtorhyncha (Ranunculus ranunculinus) |
19. Achene wall thick, smooth, papillose, or spiny; scale of nectary well-developed flap or pocket completely covering nectary. | → 20 |
20. Achenes thick-lenticular or asymmetrically thick-lenticular to compressed-globose, 1.2-2 times as wide as thick; nectary scale joined with petal on 3 sides, forming pocket enclosing nectary (sometimes with apex free, forming flap shorter than pocket); basal leaves various, unlobed to deeply divided, margins entire to crenate but never at all serrate. | sect. Epirotes |
20. Achenes strongly flattened, at least 3-15 times as wide as thick; nectary scale free from petal for at least 1/2 its length, thus forming free scale over nectary (scale sometimes free for less than 1/2 its length in R. recurvatus, with serrate to crenate-serrate leaf margins); basal leaves always deeply lobed or compound (except sometimes in R. marginatus and R. orthorhynchus), margins various. | → 21 |
21. Achenes papillose or spiny (sometimes smooth in R. sardous); flowers small, petals 1-6 mm, scarcely longer than sepals, sometimes absent (larger and much longer than sepals in R. sardous). | sect. Echinella |
21. Achenes smooth, glabrous or pubescent; flowers small to large, petals always present, 2-22 mm. | sect. Ranunculus |
1. Petals 2-6 mm, usually no longer than sepals (sometimes longer than sepals in R. uncinatus). | → 2 |
1. Petals (6-)7-26 mm (rarely shorter in R. occidentalis and R. canus, in which petals are much longer than sepals). | → 5 |
2. Basal leaves simple and lobed or parted. | → 3 |
2. Basal leaves compound. | → 4 |
3. Receptacle glabrous; base of stem not bulbous; w North America. | R. uncinatus |
3. Receptacle hispid; base of stem bulbous, cormlike; e North America. | R. recurvatus var. recurvatus |
4. Petals 2-4 × 1-2.5 mm; heads of achenes cylindric, 5-7 mm wide. | R. pensylvanicus |
4. Petals 4-6 × 3.5-5 mm; heads of achenes globose to ovoid, 7-10 mm wide. | R. macounii |
5. Sepals spreading, sometimes reflexed from base with age. | → 6 |
5. Sepals reflexed along well-defined transverse fold 1-3 mm above base. | → 12 |
6. Basal leaves deeply parted or dissected, ultimate segments linear to broadly linear, margins entire (occasionally a lobe reduced to large tooth); Rocky Mountains. | R. acriformis var. acriformis |
6. Basal leaves variously parted or compound but not as above, segments seldom linear, margins toothed; widespread. | → 7 |
7. Leaf blades simple, 3-5-parted or -divided. | → 8 |
7. Leaf blades 3-5-foliolate. | → 9 |
8. Basal leaf blades pentagonal in outline; beak of achene 0.2-1 mm; widespread. | R. acris |
8. Basal leaf blades cordate to reniform in outline; beak of achene 1.6-2 mm; Mackenzie Delta to ne Alaska. | R. turneri |
9. Tuberous roots present. | → 10 |
9. Tuberous roots absent. | → 11 |
10. Petals 10-22; c Texas. | R. macranthus |
10. Petals 5(-7); widespread, e North America. | R. fascicularis |
11. Beak of achene curved, 0.8-1.2 mm; stems decumbent to creeping. | R. repens |
11. Beak of achene straight or somewhat curved, 0.8-2.6 mm; stems erect to decumbent. | R. hispidus |
12. Petals 8-22; Pacific Coast, Arizona, Texas. | → 13 |
12. Petals 5-7; widespread. | → 17 |
13. Tuberous roots absent; beak of achene lanceolate to deltate-apiculate, curved, 0.2-1.6 mm; California to British Columbia. | → 14 |
13. Tuberous roots present; beak of achene subulate, straight, (1.8-)2-4 mm (but sometimes deciduous); Texas, Arizona. | → 16 |
14. Achenes 3.4-4.2 mm, beak deltate or lance-deltate; Transverse Ranges, s California. | R. canus var. ludovicianus |
14. Achenes 1.8-3.2 mm, beak lanceolate; California to British Columbia. | R. californicus |
15. Beak of achene 1.2-1.6 mm; sepals 5-6; Queen Charlotte Islands, British Columbia. | R. occidentalis var. hexasepalus |
15. Beak of achene 0.2-0.8 mm; sepals 5; California, Oregon, Mexico. | R. californicus |
16. Petals 2-5 mm wide; achenes 2-2.4 mm wide, margins forming ribs or narrow wings 0.1-0.4 mm wide; sepals always reflexed; Arizona, trans-Pecos Texas. | R. fasciculatus |
16. Petals 4-9 mm wide; achenes 2.8-3.4 mm wide, margins forming narrow ribs 0.4-0.6 mm wide; sepals spreading or weakly reflexed; Edwards Plateau, Texas. | R. macranthus |
17. Receptacle glabrous; basal leaves 3-parted or -foliolate, segments or leaflets linear to cuneate. | → 18 |
17. Receptacle hispid; basal leaves usually pinnately 3-7-foliolate (sometimes merely 3-parted with orbiculate to ovate segments in Ranunculus orthorhynchus var. bloomeri). | → 21 |
18. Beak of achene deltate or lance-deltate, curved; Sacramento Valley, California. | R. canus var. canus |
18. Beak of achene lanceolate to lance-subulate, straight or curved; widespread. | → 19 |
19. Basal leaves deeply 3-divided, segments again deeply parted, ultimate segments linear or nearly so; Rocky Mountains. | R. acriformis var. montanensis |
19. Basal leaves deeply 3-parted to 3-foliolate, margins of segments or leaflets toothed or shallowly lobed, ultimate lobe triangular or broadly lanceolate; Pacific Slope. | → 20 |
20. Petals yellow on both surfaces; widespread. | R. occidentalis |
20. Petals reddish abaxially; sw Oregon. | R. austro-oreganus |
21. Beak of achene oblong or triangular, curved, 0.2-0.8 mm; introduced weeds. | → 22 |
21. Beak of achene lanceolate or subulate, straight or somewhat curved (sometimes tip weakly hooked in R. pacificus), (0.8-)1-3.8(-4.8) mm; native. | → 23 |
22. Base of stem bulbous, cormlike; petals 9-13 × 8-11 mm. | R. bulbosus |
22. Base of stem not bulbous; petals 7-10 × 4-8 mm. | R. sardous |
23. Stems decumbent, sometimes rooting at nodes; e North America. | R. hispidus var. nitidus |
23. Stems erect to decumbent, never rooting at nodes; w North America. | → 24 |
24. Beak of achene 1-1.8 mm; leaflets lobed; Alaska panhandle. | R. pacificus |
24. Beak of achene 2-3.8(-4.8) mm (1.8-2.2 mm in var. bloomeri, with unlobed leaflets); throughout w North America. | R. orthorhynchus |
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