Native Range Maps
Shrub native range maps:
USDA, NRCS. 2019. The PLANTS Database (http://plants.usda.gov, 25 February 2019). National Plant Data Team, Greensboro, NC 27401-4901 USA.
Native range maps for trees and some large shrubs:
The U.S. Department of Agriculture began recording native tree species distributions in the 1880s and this work continued after the Forest Service was created in 1905. Though E.L. Little’s maps were published in the 1970s, they are the culmination of this effort. These maps attempt to show species distribution when the effect of European settlement was thought to be negligible. According to Little, records of planted or introduced populations outside of continuous natural ranges, have been omitted or not knowingly included.
Little, E.L. (1971) Atlas of United States Trees Volume 1. Conifers and Important Hardwoods. Washington D.C.: USDA Forest Service.
Little, E.L. (1976) Atlas of United States Trees Volume 3. Minor Western Hardwoods. Washington D.C.: USDA Forest Service.
Little, E.L. (1977) Atlas of United States Trees Volume 4. Minor Eastern Hardwoods. Washington D.C.: USDA Forest Service.