Studies of the seasonal course of carbon uptake of Eriophorum vaginatum in a moorland habitat. II. The seasonal course of photosynthesis

(1) The seasonal pattern of photosynthesis of different age-classes of leaves of Eriophorum vaginatum was followed in the northern Pennines between May and October 1979. (2) Photosynthetic rates in two classes of overwintering leaves at the start of the season were 40-50% of the maximum rate observed over the whole season. The younger age-class continued to fix CO2at appreciable rates until September. (3) By late June 1979, a new season's crop of leaves had developed with photosynthetic rates of 0.29-0.35 mg m-2s-1; these were more than twice the rates of the overwintering leaves. Their photosynthetic rates declined towards the end of the season partly because of a deterioration in environmental conditions and partly because of leaf senescence. (4) The seasonal pattern of leaf development and photosynthetic capacity is compared with that of other graminoid species growing in similar environments.