Growth characteristics of teasel (Dipsacus fullonum L.)

Growth characteristics of teasel, especially habits of branching and flowering, were investigated using a Japanese strain. The optimum germination temperature was 24-28°C. There was a little difference in growth and flowering among the plants sown at the ends of March, April, May and June. The ratio of bolting and flowering, which was 100% in plants sown until the end of June, decreased markedly in plants sown at the ends ot July and August and 0% in plants sown at the ends of September and November. Two primary branches grew oppositely on the respective upper 4 to 7 nodes of main stem. The secondary branches grew oppositely on the nodes of the primary branches, the third on the secondary and the fourth on the third. On the tips of these branches set one capitulum. Some of the secondary, third and fourth branches did not grow or did not set capitulum. One plant set 60 to 100 capitula. The capitulum of the main stem flowered first. The higher was the order of the branch, the later the capitulum flowered. The latest capitulum flowered 40 days later than that of the main stem. In the main stem, flower bud differentiation occurred early in February and flowering began early in June. When the main stem and branches except the upper 8 primary branches were excised, the capitula set on the remained 8 branches became similar in flowering date and in size.