Flora of North America species comparison

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Ranunculaceae

buttercup family, crowfoot family
Habit Herbs, sometimes woody or herbaceous climbers or low shrubs, perennial or annual, often rhizomatous.
Stems

unarmed.
Leaves

blade undivided or more commonly divided or compound, base cordate, sometimes truncate or cuneate, margins entire, toothed, or incised;

venation pinnate or palmate.
Inflorescences

terminal or axillary, racemes, cymes, umbels, panicles, or spikes, or flowers solitary, flowers pedicellate or sessile.
Flowers

bisexual, sometimes unisexual, inconspicuous or showy, radially or bilaterally symmetric;

sepaloid bracteoles absent;

perianth hypogynous;

sepals usually imbricate, 3-6(-20), distinct, often petaloid and colored, occasionally spurred;

petals 0-26, distinct (connate in Consolida), plane, cup-shaped, funnel-shaped, or spurred, conspicuous or greatly reduced;

nectary usually present, rarely absent;

stamens 5-many, distinct;

anthers dehiscing longitudinally;

staminodes absent (except in Aquilegia and Clematis);

pistils 1-many;

styles present or absent, often persistent in fruit as beak.
Fruits

achenes, follicles, or rarely utricles, capsules, or berries, often aggregated into globose to cylindric heads.
Seeds

1-many per ovary, never stalked, not arillate;

endosperm abundant;

embryo usually small.

Ranunculaceae
Distribution
Worldwide
[BONAP county map]
Discussion

Genera ca. 60, species 1700 (22 genera, 284 species in the flora).

The flowers of many species of Ranunculaceae begin to open long before anthesis, while the floral organs are just partly expanded. Only mature flowers with open anthers should be used for determination of diagnostic characteristics (especially measurements).

The literature is inconsistent about the term for the whorl of organs between sepals and stamens; these may be conspicuous and petaloid, or reduced to stalked nectaries, or intermediate between the two states. They have been called petals, honey-leaves, or (when they are inconspicuous) staminodes or nectaries. We follow M. Tamura (1993) and treat as petals all organs between the sepals and stamens, except in Clematis and Aquilegia where they usually bear rudimentary anthers and clearly represent staminodes.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Flowers bilaterally symmetric; sepals showy; petals smaller than sepals.
→ 2
1. Flowers radially symmetric; sepals showy or not; petals present or absent, smaller to larger than sepals.
→ 4
2. Upper (adaxial) sepal (hood) saccate or helmet-shaped; petals completely hidden by sepals.
Aconitum
2. Upper (adaxial) sepal spurred; petals at least partly exserted from calyx.
→ 3
3. Perennials; pistils 3(-5); petals 4, distinct.
Delphinium
3. Annuals; pistil 1; petals 2, connate.
Consolida
4. Fruits achenes or utricles; ovule 1 per pistil.
→ 5
4. Fruits follicles, capsules, or berries; ovules 2 or more per pistil (1 of 2 aborting in Xanthorhiza, leaving 1 seed at maturity).
→ 12
5. Sepals spurred; leaves all basal, blade linear or narrowly oblanceolate.
Myosurus
5. Sepals plane; leaves either not all basal, or blade not linear or narrowly oblanceolate.
→ 6
6. Leaves all cauline and opposite; stems ±woody, at least at base.
Clematis
6. Leaves cauline and alternate (rarely opposite), or basal, or plants with basal leaves and opposite or whorled involucral bracts; stems herbaceous.
→ 7
7. Plants with 1 or more pairs (opposite) or whorls of involucral bracts, these leaflike or calyxlike.
→ 8
7. Plants without involucral bracts (inconspicuous, linear-lanceolate involucral bracts in Trautvetteria), cauline leaves if present alternate (rarely a pair of opposite, unlobed leaves in Ranunculus sect. Flammula).
→ 9
8. Achenes with conspicuous veins or ribs on lateral surfaces; style absent.
T. thalictroides
8. Achenes without veins on lateral surfaces; style present.
Anemone
9. Petals absent; inflorescences panicles, racemes, or corymbs (umbels in Thalictrum thalictroides); filaments filiform or dilated distally.
→ 10
9. Petals present (rarely absent in Ranunculus pedatifidus); inflorescences simple or compound cymes or flowers solitary; filaments filiform.
→ 11
10. Leaves simple, blade lobed; flowers bisexual; inflorescences corymbs.
Trautvetteria
10. Leaves compound; flowers unisexual or bisexual; inflorescences panicles, racemes, corymbs, or umbels.
Thalictrum
11. Petals without nectaries; sepals 5(-8).
Adonis
11. Petals with basal nectaries; sepals 3-5(-6).
Ranunculus
12. Leaves dissected into linear, threadlike segments; pistils compound; fruits capsules.
Nigella
12. Leaves not dissected, if parted or compound the segments not linear; pistils simple; fruits aggregates of follicles or solitary or aggregate berries.
→ 13
13. Shrubs; beak of follicle lateral, strongly incurved against abaxial surface of follicle.
Xanthorhiza
13. Herbs; beak of follicle, if present, terminal or nearly so, straight or slightly curved, sometimes hooked at tip.
→ 14
14. Petals prominent, spurred.
Aquilegia
14. Petals if present inconspicuous, plane or funnel-shaped.
→ 15
15. Flowers 12-50, in racemes or racemelike panicles.
→ 16
15. Flowers 1-10, in leafy cymes or solitary.
→ 17
16. Pistils 1-8; fruits follicles, usually aggregate; petals 2-cleft or absent.
Cimicifuga
16. Pistil 1; fruits berries; petals unlobed.
Actaea
17. Leaves simple, blade often lobed 1/2-3/4 its length, margins entire, crenate, or toothed; petals absent.
→ 18
17. Leaves compound or divided to base; petals usually inconspicuous (absent in Enemion).
→ 19
18. Leaf blades unlobed, margins entire, dentate, or crenate; fruits follicles.
Caltha
18. Leaf blades lobed, margins serrate; fruits berries.
Hydrastis
19. Leaves ternately 1-2× compound.
→ 20
19. Leaves palmately or pedately compound or divided.
→ 21
20. Leaves all basal; leaf blade deeply divided, ternately or pinnately 1-2× compound; petals present.
Coptis
20. Leaves basal and cauline; leaf blade ternately 2× compound; petals absent.
Enemion
21. Leaf segments lobed, margins sharply toothed; sepals persistent in fruit.
Helleborus
21. Leaf segments cleft or parted, margins entire or toothed; sepals not persistent in fruit.
→ 22
22. Cauline leaves absent except for whorl of 3 involucral bracts immediately subtending flower; follicles stipitate.
Eranthis
22. Cauline leaves alternate, (0.8-)1 cm or more from flower, involucral whorl absent; follicles sessile.
Trollius
Source FNA vol. 3, p. 85. Authors: Alan T. Whittemore, Bruce D. Parfitt.
Parent taxa
Subordinate taxa
Aconitum, Actaea, Adonis, Anemone, Aquilegia, Caltha, Cimicifuga, Clematis, Consolida, Coptis, Delphinium, Enemion, Eranthis, Helleborus, Hydrastis, Myosurus, Nigella, Ranunculus, Thalictrum, T. thalictroides, Trautvetteria, Trollius, Xanthorhiza
Name authority Jussieu
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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