Roots yellow to light brown, fibrous, from stout caudex. Stems erect, 30-80 cm, glabrous or glandular. Leaves basal and cauline, petiolate. Leaf blade 1-4×-ternately compound; leaflets reniform or cordate to obovate or orbiculate, apically 3-12-lobed, 10-45 mm wide, lobe margins often crenate, surfaces abaxially glabrous or glandular. Inflorescences terminal and axillary, panicles to corymbs, many flowered. Flowers: sepals greenish to purple, ovate or obovate to oval, 1.8-4 mm; filaments yellow to greenish yellow, 3.5-5.5 mm; anthers 2-4 mm, mucronate to acuminate; stigma purple. Achenes (3-)7--13, not reflexed, sessile or nearly so; stipe terete, 0-0.2 mm; body ovoid to ellipsoid, not laterally compressed, 3.5-5 mm, glabrous, very strongly veined, veins not anastomosing-reticulate; beak 1.5-3 mm.
Flowering spring (Apr-Jun). Rocky woods, ravines, and alluvial terraces, mountains and piedmont; 10-1000 m; Man., Ont., Que.; Ala., Conn., D.C., Ga., Ill., Ind., Iowa, Kans., Ky., Maine, Md., Mass., Mich., Minn., Mo., Nebr., N.H., N.J., N.Y., N.C., N.Dak., Ohio, Pa., R.I., S.C., S.Dak., Tenn., Vt., Va., W.Va., Wis.
Glandular plants of Thalictrum dioicum have often been misidentified as T . revolutum despite important differences, especially the leaflets having crenate versus entire lobe margins, respectively. The stamens in both T . dioicum and T . revolutum are pendulous.
Native Americans used roots of Thalictrum dioicum in various preparations to treat diarrhea and vomiting and for heart palpitations (D. E. Moerman 1986).
Generally frequent throughout the state on wooded slopes. This species, like the others, shows considerable variation but I believe we do not have any of the described varieties or closely allied species. My [Deam] no. 5946, collected on the bank of Wildcat Creek west of Greentown in Howard County, I cite as unusual. My specimen arises from a node of an underground stem. The stem remaining on the specimen has nine nodes and is 16 cm long, and shows no decrease in size where it has been broken off at both ends.
Plants dioecious, 3-7 dm at anthesis; stem arising from a subterranean, fibrous-rooted crown; lvs glabrous, thin, flat-margined; petioles all elongate, the uppermost 3-6 cm and subtending the infl; stipules of upper lvs broadly ovate to semicircular or semilunate, mostly much wider than long; filaments and anthers yellow or greenish-yellow; achenes sessile or subsessile, 4 mm, strongly ribbed, straight and essentially symmetrical; 2n=28, 42. Abundant in moist woods; Que. to Man., s. to S.C., Ga., Ala., and Mo. Fl with or before the expansion of the lvs on deciduous trees.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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