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Pacific Southwest Research Station
800 Buchanan Street
Albany, CA 94710-0011
Publications and Products
Title: Pinus ponderosa: a taxonomic review with five subspecies in the United States.
Author: Callaham, Robert Z.
Source: Res. Pap. PSW-RP-264. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 29 p.
Station ID: RP-PSW-264
Description: Various forms of Pinus ponderosa Douglas ex C. Lawson are found from British Columbia southward and eastward through 16 states and, perhaps, into Mexico. The status of many names previously associated with this species, but excluded here, has been clarified. Accumulated evidence based on variation in morphology and xylem monoterpenes, partial genetic barriers to crossing, and allozyme differences leads to recognition of five subspecies:
Transition zones occur between subspecies.
Key Words: Ponderosa pine, Pinus ponderosa, taxonomy, subspecies
Callaham, Robert Z. 2013. Pinus ponderosa: a taxonomic review with five subspecies in the United States. Res. Pap. PSW-RP-264. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 52 p.
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