© 1990 Heron Publishing—Victoria, Canada
Influence of male cones on early season vegetative growth of Pinus contorta trees
J. McP. Dick (1), P. G. Jarvis (2) and R. R. B. Leakey (1)
1. Institute of Terrestrial Ecology, Bush Estate, Penicuik, Midlothian EH26 0QB, Scotland / 2. Department of Forestry and Natural Resources, University of Edinburgh, Mayfield Road, Edinburgh, EH9 3JH Scotland / Received May 25, 1989
Summary
On average, branches of Pinus contorta Dougl. bearing male cones had 35 fewer needle pairs than equivalent vegetative branches, and significantly fewer differentiated
primordia (i.e., male cones + needle pairs + sterile cataphylls). It was estimated that the formation of male cones results
in a 27–50% reduction in the number of needles per male cone-bearing branch. In early spring, branches bearing male cones
had on average 23% (0.44 g) more dry weight than vegetative branches. On average, 95% of the dry weight of male cone-bearing
branches was allocated to the terminal shoot (54% of which was male cones) and 5% to the lateral shoots. By comparison, vegetative
branches allocated 85% of their total dry weight to the terminal shoot and 15% to the lateral shoots. These findings suggest
that male cones may reduce the photosynthetic potential of the trees which bear them.
