Leaves of carrot plants of cultivated varieties contained an average of 119 mg. of total carotene per kg. fresh weight, or 546 mg. per kg. dry weight. The concentration of total carotene based on averages of many batches was approximately constant through the season so long as the leaves remained healthy in appearance, and except for small seedlings, was independent of the age of the plant. The average concentration was the same during three successive years. In these respects leaves contrasted with roots. There was, however, a variation between individual batches from different varieties, seasons and growing conditions. A measure of this overall variation is given by the standard deviation, 19 mg. per kg. fresh weight. Part of this variation was due to experimental error of the analytical method, and part to sampling. Beyond these there was a residual variation between different batches which has not been explained.
The concentration of leaf total carotene was independent of variety among cultivated types of carrot. There was no correlation between carotene concentrations in leaf and in root although the latter varied several hundredfold in different varieties, which included deep red, orange and white types.