The family Gentianaceae in Utah includes the genera Gentiana, Gentianella, Centaurium, Frasera, and Swertia and is composed of 15 species. Centaurium nuttallii S. Watson is placed in synonymy under C. exaltatum (Griseb.) Wight, because there is no clear-cut basis for its segregation at the species level. Similarly, Gentiana forwoodii Gray and G. parryi Engelm. are extremes of clinal variation in G. affinis and are synonymized there. Keys to the genera, species, and subspecies are provided, as well as distribution maps, descriptions, and synonymies.
Allred, Kelly W.
"The plant family Gentianaceae in Utah,"
Great Basin Naturalist: Vol. 36
, Article 11.
Available at: http://scholarsarchive.byu.edu/gbn/vol36/iss4/11