Cauline lvs mostly at least 8 times as long as wide and long-tapering to the base, the blade sessile or merging gradually into the short, poorly differentiated petiole, rarely less than 7 cm (petiole included); 2n=12-72+. Rich woods and fields; N.S. to Minn., s. to Ga., La., and Tex. Early spring, disappearing by midsummer. Two weakly defined vars.: var. virginica (C. media, C. robusta), with lvs mostly 5-10(-20) mm wide, and with chromosome numbers based eventually on x=8, is the more n. phase, and var. acutiflora DC. (C. simsii), with the lvs mostly 1-4 mm wide and with chromosome numbers based eventually on x=6, is the more s. phase, but both vars. are well represented in much of our range.
Yellow-fld plants related to var. virginica are locally and sporadically distributed in N.J., Pa., and Md. The oldest name for these is C. virginica f. lutea R. J. Davis, based on plants from Md. These and the Pa. plants occur in mixed and intergrading populations with typical C. virginica. The N.J. plants, at least, occur in wetter, shadier habitats than is typical of C. virginica, and last throughout much of the summer. These have been called f. hammondiae Kalmb. Further study is in order.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.