Variation in natural populations ofPinus radiatain California

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Abstract
As part of a study of variation in the three Californian populations of Pinus radiata, measurements were taken from closed cones bisected longitudinally along the plane of bilateral symmetry. These included the length and diameter of the axis, the breadth of the whole cone, and the len~th of scales and thickness (If apophyses on the inner and outer sides. The Cambria cones are the largest in all these dimensions and the Monterey cones the smallest, while cones from Año Nuevo Point are intermediate. The average breadth/length ratio of the cones is much the same in the three population but differs greatly in individual trees. Most of the variation arises from differences in the relative diameter of the axis rather than in the relaitive length of the scales. The number of scales per cone was estimated by counting those in one parastichy, and is significantly higher in Cambria cones than in the other two populations. Conversely, the average spacing of the scales on the axis is significantly closer, and the scales therefore smaller. in the Monterey population than in the other two. The curvature of the cone axis varies greatly from tree to tree, but is similar in average value in all the populations. The average development of the outer apophyses relative to the inner is significantly greater at Cambria than in the other two populations, and also greater at Año Nuevo Point than at Monterey. Lateral asymmetry in bnth apophysis thickness and scale length is correlated with axis curvature. The cones all the populations are very variable in the morphology of the apophyses, umbos, and mucros. The average dimensions of the seeds vary in parallel with those of the cones, and the colour of both seed and wing is cons picuously variable in all populations.

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