We examine patterns of variation in 12 continuous morphological traits, chloroplast DNA sequences from 10 intergenic spacer regions (petA-psbJ, psbk-trnS, psbM-trnD, rpob-trnC, trnC-trnD, trnGCUtrnG2S, trnFM-trnUGA, atpF-atpH, trnT-trnD, trnQ-psbk), atpF, and rpl16, and Amplified Fragment Length Polymorphism (AFLP) genetic markers in Sclerocactus glaucus sensu lato (5S. brevispinus, S. glaucus,...