Much like no. 4 [Pycnanthemum incanum (L.) Michx.], but the bracts and cal-teeth not bristle-tipped; cal-lobes deltoid, the lower ca 1 mm, the upper distinctly shorter; 2n=38. Dry upland woods; se. Mo. and s. Ill. to Fla. and Tex.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.