Kimball, R.T., D.J. Crawford, J.R. Page and P. J. Harmon. 2001. Intersimple Sequence Repeat (ISSR) diversity within Monarda fistulosa var. brevis (Lamiaceae) and divergence between var. brevis and var. fistulosa in West Virginia. Brittonia 53: 511-518.

Inter-simple sequence repeat (ISSR) banding patterns, were used to examine genetic diversity within and among populations of Monarda fistulosa var. brevis, a rare taxon restricted to several populations in limestone glades and barrens in eastern West Virginia and Virginia. More than 34% of the total ISSR diversity in var. brevis occurred among populations, which is high when compared to the few other rare species that have been examined for ISSR variation. Prior studies demonstrated that var. brevis is morphologically distinct from the more widespread var. fistulosa, and that the differences are maintained when the two varieties are grown together in a uniform environment. The present study utilizing ISSR markers indicated that the two varieties are distinct, though quite similar genetically, and this is concordant with prior investigations documenting their morphological and habitat differences. However, the ISSR results suggest that the two varieties have diverged relatively recently and/or there is a low level of gene flow between them.