Stems erect, 20-50 cm, glabrous, from rhizomes. Leaves basal and cauline; cauline 1-3, those proximal to inflorescence petiolate, those subtending panicle branches sessile. Leaf blade 3-4×-ternately compound; leaflets obovate to orbiculate, apically 3-5-lobed, 5-20 mm, lobe margins crenate, surfaces abaxially glabrous or glandular-puberulent. Inflorescences terminal, panicles, narrow and dense, many flowered. Flowers: sepals greenish white, lanceolate or broadly ovate to elliptic or obovate, 2-4 mm; filaments colored, not white, (1.8-)3-5.5 mm; anthers 2-3.5 mm, blunt to mucronate; stigma commonly yellowish. Achenes 5-17, erect to spreading, not reflexed, nearly sessile; stipe 0.1-0.3 mm; body often distinctly curved, elliptic-oblong, nearly terete to slightly flattened, adaxial surface 3-4(-6) mm, glabrous to glandular, veins distinct, not anastomosing-reticulate; beak 1.5-2.5(-3) mm.
Phenology: Flowering early summer-mid summer (Jun–Aug).
Habitat: Prairies, riparian woods, and coniferous, deciduous, and mixed forests
Elevation: 600-3700 m
Alta., B.C., Man., N.W.T., Ont., Que., Sask., Yukon, Colo., Idaho, Minn., Mont., Nebr., Nev., N.Mex., N.Dak., Oreg., S.Dak., Utah, Wash., Wis., Wyo.
Thalctrum venulosum is similar to T. confine and T. occidentale. Careful field studies are needed to clarify the relationships among these taxa.