Taxonomic Notes on Houstonia purpurea var. montana (Rubiaceae)

ABSTRACT
<em>Houstonia purpurea</em> var. <em>montana</em> is restricted to the summits of Roan Mountain, North Carolina-Tennessee, and Grandfather Mountain, North Carolina. Morphological and cytogenetic data support varietal rank for it instead of specific rank as <em>H. montana</em>. Correct authorships for these names are discussed. A recent finding of sterility in crosses between <em>H. purpurea</em> var. <em>purpurea</em> and var. <em>montana</em> could have been caused by ploidy differences alone rather than by more fundamental differences. <em>Houstonia purpurea</em> var. <em>montana</em> is subjected to increasing human encroachment and should be considered as threatened or endangered.