Isopyrum biternatum (Rafinesque) Torrey & Gray. Common name: Isopyrum, False Rue-anemone. Phenology: (Jan-) Mar-Apr; May. Habitat: Rich forests, either on natural levees with very nutrient rich sediments or on slopes with underlying mafic or calcareous rocks. Distribution: Mainly west of the Appalachians, W. NY, s. ON and MN south to TN, ne. MS (Tishomingo County), and AR; disjunct east and south of the Blue Ridge in VA, NC, SC, the FL Panhandle, and s. AL. Buckingham, Singhurst, & Paez (2020) discussed its distribution in Texas.
ID notes: Isopyrum biternatum is somewhat superficially similar to the more common and widespread (in the Flora area) Thalictrum thalictroides, with which it also sometimes grows, but can be distinguished by the following characters: stem leaves 1-4 and alternate (vs. stem leaves 2 and opposite), fruit an aggregate of follicles (vs. fruit an aggregate of achenes), petaloid sepals 5 (vs. 5-10, usually some at least of the flowers on a plant with 6 or more), leaflets deeply lobed, at least some of the leaflets on a plant with sinuses at least 1/3 as long as the leaflet (vs. leaflets shallowly lobed, the notches < 2 mm long).
Origin/Endemic status: Native
Taxonomy Comments: See genus for discussion of generic placement.
Synonymy ⓘ: = C, F, G, GrPl, Mo3, RAB, S, S13, Tx; = Enemion biternatum Raf. — Ar, Can, Fl2, FNA3, Il, K4, Mi, NS, NY, POWO, Tn, Va, WH3; = n/a — Pa. Basionym: Enemion biternatum Raf. 1820
Links to other floras: = Enemion biternatum - FNA3
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Wetland Indicator Status:
- Atlantic and Gulf Coastal Plain: FACW
- Eastern Mountains and Piedmont: FACU
- Great Plains: FAC
- Midwest: FAC
- Northcentral & Northeast: FAC
Heliophily ⓘ: 2
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© Floyd A. Griffith | Original Image ⭷
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© Scott Ward | Original Image ⭷
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Horticultural Information
Intro: Delicate, erect perennial found often in dense patches in rich forests, either on natural levees with very nutrient-rich sediments or on slopes with underlying mafic rocks.
Stems: Stems slender, sparingly branched, reddish-tinged, smooth.
Leaves: Leaves basal and alternate on the stem, petiolate, divided into 3 leaflets up to 1 in. long, these again divided into 3 bluntly rounded lobes; the terminal leaflet is longer-stalked than the 2 lateral leaflets.
Inforescence:
Flowers: Flowers solitary, or in groups of 2-3, on thin stalks from leaf axils; white; consisting of 5 petal-like sepals, several slender stamens with yellow anthers and a few green pistils in the center.
Fruits: Fruit a small cluster of beaked follicles.
Comments:
Height: 8-16 in.
plant sale text:
bloom table text:
description: Delicate, erect perennial found often in dense patches in rich forests, either on natural levees with very nutrient-rich sediments or on slopes with underlying mafic rocks.
stems: Stems slender, sparingly branched, reddish-tinged, smooth.
leaves: Leaves basal and alternate on the stem, petiolate, divided into 3 leaflets up to 1 in. long, these again divided into 3 bluntly rounded lobes; the terminal leaflet is longer-stalked than the 2 lateral leaflets.
inflorescence:
flowers: Flowers solitary, or in groups of 2-3, on thin stalks from leaf axils; white; consisting of 5 petal-like sepals, several slender stamens with yellow anthers and a few green pistils in the center.
fruits: Fruit a small cluster of beaked follicles.
comments:
cultural notes:
germination code:
native range: eastern United States
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