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The percentage of clover in a mixture of Huia white clover and Mellc perennial ryegrass decreased during each of three winters. In the most severe winter, both grass and clover suffered a net loss of weight, clover losing twothirds of its maximum weight while grass lost about one-third. In the mildest winter, grass continued to gain weight throughout, while clover lost weight. Such losses, when combined with conditions such as the use of nitrogen fertilizer, which prevent a recovery of clover percentage during summer, will lead to a longterm decrease in the clover content of a sward.The losses from the clover were contributed to by all plant parts especially leaf, which lost between 60% and 95'^i) of lamina weight. The change from autumn to winter caused a greater decrease in the number of live leaves per shoot, and In the area and weight of individual leaves, in clover than in grass. Other work has shown that there is a greater decrease in photosynthesis in clover than in grass, probably owing to changes in canopy structure; this is one cause of clover's poor performance, though differences between the two species in the effect of winter on the distribution of the carbon Tixed in photosynthesis and in losses of weight in respiration and tissue death may also be involved.

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