Geographic variation in shortleaf pine (Pinus echinata Mill.) - Cortical monoterpenes

Cortical monoterpenes were assayed in bud tissue from 16 Southwide Southern Pine Seed Source Study (SSPSS) sources and from 6 seed orchard sources from across the natural range of the species, to examine geogaphic variation in shortleaf pine. Spruce pine and pond pine were also sampled. The results show geographic differences in all of the major terpenes. There was no north-south trend in any of the terpenes, but there was clinal variation in alpha pinene from west to east. One source, from New Jersey (SSPSSS) had very low alpha pinene and did not fit the trend, possibly because of hybridization with pitch pine. Some of the western sources had high limonene content, probably as a result of hybridization with loblolly pine, which has high limonene in western populations. Spruce pine had terpene levels similar to shortleaf pine, while pond pine had low alpha pinene and much higher limonene compared to shortleaf pine.