Comparisons of flowers and single petals (adaxial surface) of three Heuchera species co-occurring in PA, WV, and VA, based on spirit-preserved materials: Heuchera alba (a, d North Fork Mountain, WV; Folk 63 [deposited at OS]), Heuchera pubescens (b, e Rocky Knob Overlook, Blue Ridge Parkway, VA; Folk 100 [deposited at OS]), and unhybridized H. americana (i.e. H. americana var. americanac, f Chestoa Overlook, Blue Ridge Parkway; Folk 92 [deposited at OS]). Dotted gray lines show degree of hypanthium zygomorphy. Both scale bars represent 5 mm; the left-hand scale bar applies to a–c the right-hand bar is for d–f. Illustrations by R. Folk