Southern Research Station

Title: Distinguishing features of loblolly and shortleaf pine seeds: implications for monitoring seed production in mixed stands

Author: Shelton, Michael G.; Cain, Michael D.

Date: 1996

Source: Can. J. For. Res. 26. 2056-2055 (1996).

Description: Monitoring seed production in mixed loblolly pine - shortleaf pine (Pinus taeda L. and Pinus echinata Mill. respectively) stands may require identifying individual seeds by species. Although loblolly pine seeds are on average heavier and larger than those of shortleaf pine, there is considerable overlap in these properties for individual seeds. In this study the properties of six seed lots of each species from Arkansas and Louisiana were examined. Seed weight for loblolly pine averaged twice that of shortleaf pine, but seed length and width differed by only 13 and 27%, respectively. Seed-coat thickness was the most consistent difference observed between the two species: large shortleaf pine seeds had thinner seed coats than small loblolly seeds, but this property was slow and tedious to measure. By contrast, differences in seed-coat thickness were readily detected when conducting a cut test for seed soundness by subjectively assessing the force required to cut the seed. In a blind test, 12 evaluators estimated within ±10% of the known composition of 10-seed subsamples 86% of the time for the cut test compared with only 57% when using seed appearance alone: inexperienced evaluators were only slightly lower in accuracy than experienced ones. Use of the cut test as a subjective estimate of the force required to cut the seed appears to be reasonably accurate in distinguishing these turn species for most purposes.

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Citation

Shelton, Michael G.; Cain, Michael D.  1996.  Distinguishing features of loblolly and shortleaf pine seeds: implications for monitoring seed production in mixed stands.   Can. J. For. Res. 26. 2056-2055 (1996).