[Thalictrum confine Fernald, moreThalictrum confine var. columbianum (Rydb.) B. Boivin, Thalictrum confine var. greeneanum B. Boivin, Thalictrum occidentale var. columbianum (Rydb.) H. St.-John, Thalictrum turneri B. Boiv., Thalictrum venulosum var. confine (Fernald) B. Boivin, Thalictrum venulosum var. fissum (Greene) B. Boivin, Thalictrum venulosum var. lunellii (Greene) B. Boivin, Thalictrum venulosum var. turneri (B. Boivin) B. Boivin]
Stems erect, to 100 cm, from rhizomes. Leaves: cauline leaves 3-4, those proximal to inflorescence petiolate, those subtending panicle branches sessile. Leaf blade: leaflets reniform-cordate, apically 3-5-lobed, 15-50 mm wide, lobe margins crenate, surfaces glabrous to glandular. Inflorescences terminal, panicles, narrow with ascending branches, many flowered. Flowers: sepals yellowish to purple, oblong, 1.5-5 mm; filaments colored, not white; anthers 3-4.5 mm, mucronate; stigma purple. Achenes 4-13, erect, incurved, not reflexed, sessile; body fusiform to ovoid, not laterally compressed, adaxial surface 4-6 mm, glandular, veins prominent, not anastomosing-reticulate; beak (2-)2.5-4(-5) mm. Flowering early-mid summer (Jun-Jul). Alluvial or shingly calcareous shores and talus; 0-200 m; N.B., Ont., P.E.I., Que.; N.Y., Vt. The relationship between Thalictrum confine and T . venulosum is unclear and requires additional field study.
Stems glabrous or nearly so, arising 3-10+ dm from the upturned end of a rhizome; lvs usually at least sparsely glandular beneath, but less so than in no. 8 [Thalictrum revolutum DC.], those below the infl petioled, those subtending the panicle-branches sessile; panicle with ascending branches; body of the achene 4-6 mm, its lower margin more convex than the upper; 2n=42. Rocky or gravelly soil, often along shores; Lab. to B.C., s. to Vt., n. N.Y., n. Mich., n. Wis., n. Minn., Wyo., and Oreg. June, July. Our plants have been distinguished on dubious grounds from typical cordilleran T. venulosum as var. confine (Fernald) B. Boivin. (T. confine)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.