St. John, L.; Tilley, D.; Ogle, D. 2011. Plant guide: Firecracker penstemon (Penstemon eatonii). Aberdeen, ID: U.S Department of Agriculture, Natural Resources Conservation Service, Plant Materials Center. 4 p.
St. John, L.; Tilley, D.; Ogle, D. 2011. Plant guide: Firecracker penstemon (Penstemon eatonii). Aberdeen, ID: U.S Department of Agriculture, Natural Resources Conservation Service, Plant Materials Center. 4 p.