Sparingly branched, 3-8 dm, glabrous or nearly so; basal lvs simple, broadly ovate, usually cordate at base, or occasionally ternate like the cauline; cauline lvs ordinarily pinnate with 3(5) ovate or lanceolate, toothed lfls 4-8 cm, rarely the lateral lfls again 2-3-lobed; umbels long-peduncled, 3-8 cm wide, the 6-10 rays unequal; fr ellipsoid, 3.5-5 mm, three-fourths as wide, including the broad wings; 2n=22. Woods, R.I. to Minn. and S.D., s. to Ga., La., and Okla. May, June. Typical T. trifoliatum (T. atropurpureum), with dark purple fls, is widespread, but more common eastward. Yellow-fld plants, usually distinguished as var. flavum S. F. Blake (T. aureum, misapplied), are also widespread, but more common westward.

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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Frequent in woodland throughout the state. Usually restricted to wooded slopes along or near streams. It is to be noted that all Indiana specimens have yellow flowers. 

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Indiana Coefficient of Conservatism: C = 5

Wetland Indicator Status: UPL

Diagnostic Traits: perennial to ca. 0.6 m tall; basal leaves simple, cordate, rotund; cauline leaves ternate or simple; nodes glabrous to minutely pubescent; umbel bracts lacking or minute; flowers yellow; fruits ellipsoid, ca. 4 mm long, with prominent winged ribs.