What does ACCOH stand for?

Aconitum columbianum Nutt. var. howellii (A. Nels. & J. F. Macbr.) C. L. Hitchc. - Scientific name - Accepted name: Aconitum columbianum ssp. viviparum - Family: Ranunculaceae - USDA National Plant Data Center symbol - Botany - Taxonomy (USDA)