Differences in cone and seed morphology of pinus strobiformis and pinus ayacahuite

Abstract For decades there has been confusion and uncertainty on how to clearly identify the two distinct species, Pinus strobiformis Engelm. and Pinus ayacahuite Ehrenberg. Pinus ayacahuite is further defined as two varieties, var. ayacahuite and var. veitchii. These species are of ecological importance throughout much of Mexico because they offer valuable ecosystem services. The objective in this work was to examine the morphological characteristics of cones and seeds from parent trees from six sites in northern Mexico and three sites in southern Mexico. The results show that the mean seed width and length per tree, mean cone weight per tree, and the 100-seed weight per tree were the best variables to accurately separate P. strobiformis from P. ayacahuite. Using these criteria, we found that P. ayacahuite var. veitchii is more similar to P. strobiformis than to P. ayacahuite var. ayacahuite.