This is widespread on medium acid soils in southeastern states but perhaps absent west of the Mississippi Rv. (Wasshausen 1998). Intraspecific taxa have not been recognized in most recent treatments, but variation deserves further study; F recognized 11 infraspecific taxa. Records mapped here include many colls. that have been referred to var. parviflora (Nees) Blake. A coll. from SCOT (DHL) was referred to var. membranacea Fern. See also notes under humilis, which may intergrade with caroliniensis; and there has been confusion with R. ciliosa Pursh.. Note that only one chromosome number (2n= 34) has been reported for North American Ruellia.