In order to know the appropriate harvest time in the cultivation of the medicinal plant, M chamomilla L., we investigated seasonal variations in the yield of the head (capitula) and the content of two phenylpropanoid glycosides ; cis-(1) and trans-2-β-D-glucopyranosyloxy-4-methoxy cinnamic acid (2) and one flavonoid glycoside ; cosmosiin (3) in the head for three months of the flowering time from May to July in 1993. The maximum head size was observed at the beginning of May, and then the size decreased as the development of ligulate flowers retarded. But tubular flowers did not decrease significantly. The content of 1 was the highest among the three glycosides during the flowering time. The values were about 2.0% and 0.5% for 1 and 2, respectively, from the end of May to the middle of June. Then the content of 1 decreased rapidly but 2 decreased gradually. The decline of these two kinds of glycoside was accompanied with a diminution of the ligulate flowers. The content of 3 became higher in an early time. The results showed that the appropriate time for the harvest of the head for the crude drug were from the beginning of May to the middle June. After this time, though external appearance of the head were unfavorable, the content of 1+2 was at the same level as that in the commercial flowers.
