Flora of North America species comparison

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Enemion

Enemion biternatum

anemone, false rue-anemone

eastern false rue anemone, false rue anemone
Habit Herbs, perennial, from stout woody rhizomes or tuberous roots.
Stems

10-40 cm, weakly rhizomatous;

roots fibrous.
Leaves

blade 2-ternately compound;

leaflets broadly ovate to cuneate-obovate, margins entire to deeply 3-notched.

leaflets irregularly 2-3-lobed, lobes sometimes with 1-3 secondary lobes, apex rounded, glandular-apiculate;

surfaces abaxially glabrous.
Inflorescences

terminal or axillary, 2-10-flowered cymes or racemes or flowers solitary, to 4 cm;

bracts absent.

axillary, flowers solitary or loosely grouped in 2-4-flowered leafy racemes;

peduncle not strongly clavate.
Flowers

bisexual, radially symmetric;

sepals not persistent in fruit, 5(-9), white, occasionally tinged pinkish, plane, ovate to obovate, 3.5-15 mm;

petals absent;

stamens 9-75;

filaments filiform to clavate or narrowly triangular;

staminodes absent between stamens and pistils;

pistils [1-]2-10, simple;

ovules 2-6 per pistil;

style present.

sepals 5.5-13.5 × 3.5-8.5 mm;

stamens 25-50;

filaments filiform to club-shaped, 1.8-5.8 mm.
Fruits

follicles, aggregate, sessile or stipitate, oblong or elliptic to obovate, laterally compressed, sides with a few prominent veins and transverse veinlets;

beak terminal, straight or curved, 0.5-3 mm.

Seeds

reddish brown, ovoid, smooth, rugulose, or minutely pubescent.

2.1-2.7 mm, minutely pubescent.
Follicles

sessile, upright to widely divergent;

body widely elliptic to widely obovate, 3.5-6.5 mm, gradually contracted into style beak;

beak 1.7-3 mm.
x

= 7.

2n

= 14.

Enemion

Enemion biternatum
Phenology Flowering spring.
Habitat Moist deciduous woods of valleys, flood plains, and ravine bottoms, occasionally in open pastures, often on limey soils
Elevation 25-1000 m (100-3300 ft)
Distribution
from USDA
North America; Asia
[BONAP county map]
from FNA
AL; AR; FL; IA; IL; IN; KS; KY; MI; MN; MO; MS; NC; NY; OH; OK; SC; SD; TN; VA; WI; WV; ON
[WildflowerSearch map]
[BONAP county map]
Discussion

Species 6 (5 in the flora).

The delimitation of taxa within tribe Isopyreae Schrödinger has been open to considerable debate. North American taxonomists tend to retain the North American species in Isopyrum Linnaeus whereas taxonomists elsewhere recognize Enemion along with a number of other segregate genera [e.g., Dichocarpum (Tamura and Kosuge) W. T. Wang and Fu D.-Z., Isopyrum in the strict sense, Leptopyrum Reichenbach, and Paraquilegia Drummond and Hutchinson] (J. R. Drummond and J. Hutchinson 1920; Fu D.-Z. 1990; M. Tamura 1984, 1993; M. Tamura and L. A. Lauener 1968).

Enemion has no petals and is regarded as the most primitive member in tribe Isopyreae (D.-Z. Fu 1990; M. Tamura 1984; M. Tamura and L. A. Lauener 1968). The other closely related genera form a transition series: Dichocarpum has peltate petals similar to the stamens; Isopyrum and Leptopyrum possess peltate petals with larger, tubular limbs and shorter claws; and Paraquilegia has nonpeltate petals that are flat and ± concave or swollen near the base and nearly sessile.

While some authors have argued that too much emphasis has been placed on petals as characters for segregating genera (e.g., J. A. Calder and R. L. Taylor 1963), Enemion is a well-defined taxon, easily distinguished from other members of tribe Isopyreae. Final decisions involving the circumscription of Enemion await molecular study involving all members of subfamily Isopyroideae Tamura.

All species of Enemion in the flora, with the exception of E. biternatum, are localized endemics of western North America from British Columbia to California.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Enemion biternatum has been mistaken for the superficially similar Thalictrum thalictroides because of its white flowers and compound Thalictrum-like leaves. Enemion biternatum is easily distinguished, however, by its few-seeded follicles and deeply lobed leaves with glandular-apiculate apices. Thalictrum thalictroides, on the other hand, is characterized by having achenes and somewhat crenate leaves with notched apices.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Inflorescences terminal or axillary, well-defined 3–10-flowered cymes with small scalelike bracts; leaflets abaxially pubescent.
E. hallii
1. Inflorescences axillary, flowers solitary or loosely grouped in 2–4-flowered leafy cymes or racemes, bracts similar to distal stem leaves; leaflets abaxially glabrous.
→ 2
2. Follicles stipitate; peduncle strongly clavate; stamens fewer than 15, filaments flat, narrowly triangular.
E. stipitatum
2. Follicles sessile; peduncle not clavate; stamens more than 20, filaments filiform to club-shaped.
→ 3
3. Lobes of leaflets with shallow glandular notches at apices; sepals (10–)12.6–15(–16.8) mm; follicle bodies 11–15 mm; coastal British Columbia.
E. savilei
3. Lobes of leaflets glandular-apiculate; sepals 5.5–13.5 mm; follicle bodies 3.5–11.5 mm; California, c, e North America.
→ 4
4. Follicle body 3.5–6.5 mm, gradually contracted into style beak; beak 1.7–3 mm; seeds 2.1–2.7 mm, minutely pubescent; roots fibrous; c, e North America.
E. biternatum
4. Follicle body (7.7–)8.5–11.5mm, abruptly contracted into style beak; beak 0.8–1.7mm; seeds 1.5–2mm, glabrous; roots tuberous; c, s California.
E. occidentale
Source FNA vol. 3. Author: Bruce A. Ford. FNA vol. 3.
Parent taxa Ranunculaceae Ranunculaceae > Enemion
Sibling taxa
E. hallii, E. occidentale, E. savilei, E. stipitatum
Subordinate taxa
E. biternatum, E. hallii, E. occidentale, E. savilei, E. stipitatum
Synonyms Isopyrum biternatum
Name authority Rafinesque: J. Phys. Chim. Hist. Nat. Arts 91: 70. (1820) Rafinesque: J. Phys. Chim. Hist. Nat. Arts 91: 70. (1820)
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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