Component analysis was applied to the interpretation of (a) leaf analyses from six similar groundnut fertilizer trials, and (b) the chemical composition of different parts (root, stem and successive leaves) of the sugar cane plant. For each of the groundnut trials it was found that approximately 60 per cent of the total variation in N, P, K, and Ca could be accounted for by two independent linear functions of the elements, representing the balance of N and K with Ca and the balance of N with P and K. The second of these functions was consistently affected by phosphorus applications. Yield was related to one or other function, according to trial, but never to them both. Throughout the sugar cane plant the elements N, P, K, Ca, and Mg were found to be distributed between the roots and the aerial parts, and between active photosynthetic and non-photosynthetic tissues. In both cases the result was a reasonable and consistent simplification of a considerable body of data, such as had not resulted from a series of univariate analyses of variance.