Photosynthesis in Sitka spruce (Picea sitchensis (Bong.) Carr.) IX. The relative contribution made by needles at various positions on the shoot.
The insertion angle of the needles, their position on the stem, and their width had large effects on the uptake of 14CO2 by detached 'sun' and 'shade' shoots. Differences between 'sun' and 'shade' shoots were much smaller than between 'sun' and 'shade' needles [see preceding abstract].