This is a variable southeastern species that may introgress with other species (Cr, Y), especially L. aspera (see notes under that species) and locally L. scariosa (L). Willd. Hybrids are relatively frequent within this genus, which has a consistent chromosome number; 2n = 20 in virtually all reports. However, no simple hybrids of squarrulosa appear to have been named (FNA 21). Relatively hairy plants, formerly known as L. scabra (Greene) K. Schum., are included here. There has been confusion with typical scariosa, which is often difficult to distinguish from squarrulosa or transitions to aspera. L. scariosa has generally larger heads (20-80 flowers versus 10-30) and longer peduncles (mostly 8-50 mm versus 0-8 mm), compared to those two species. It occurs further east in Appalachian regions, especially around the shale-barrens of Pa., Md., W.Va. and Va; it extends south to the mountains of Tenn. and N.Car (W). Reports of scariosa from Ky. (including K) are erroneous (M).