The combination Artemisia tridentata Nutt. ssp. spiciformis (Osterhout) Goodrich & McArthur comb. nov. is made. This high elevation taxon was originally described at the species level and more recently has generally been treated as a form of A. tridentata ssp. vaseyana. The subspecies designation is supported by its parallel nature to the other A. tridentata subspecies and by its relatively widespread and locally abundant populations. Also, a new variety of A. tridentata ssp. vaseyana is proposed.
Goodrich, Sherel; McArthur, E. Durant; and Winward, Alma H.
"A new combination and a new variety in Artemisia tridentata,"
Great Basin Naturalist: Vol. 45
, Article 14.
Available at: http://scholarsarchive.byu.edu/gbn/vol45/iss1/14