Biosystematics of the genus Pinus, subsection contortae

Gene frequency data from 42 isoenzyme loci were used to assess the phylogeny of taxa in the genus Pinus, subsection Contortae. The classification inferred from a phenogram based on Nei's genetic distance measure (D_N) was generally in good agreement with the current taxonomic treatment of the subsection. Pinus contorta appears to most closely resemble the ancestral taxon from which all other taxa in the subsection are derived. An alternative classification based upon Mahalonobis squared distances (D_R) obtained from seed and cone measurements differed from the isoenzyme treatment by placing P. contorta subsp. murrayana in close association with P. virginiana.