Effects of Photoperiod and Temperature on Growth and Development of Kok-saghyz

1. Flower primordia were present on plants of Taraxacum kok-saghyz collected from several localities in the central or northern parts of the United States during the late fall or winter months. Photoperiods of 8, 10, 12, 14, 16, and 18 hours did not inhibit the development of these primordia into mature flowers when the plants were transplanted in the greenhouses. 2. Wide variability of leaf pattern was observed in the seedlings, but morphological characteristics of the flowers indicated that almost all were kok-saghyz plants. Seedling plants subjected to six different lengths of photoperiods varying from 8 to 18 hours flowered under all conditions, but more of them flowered with photoperiods of 12 hours or longer than with shorter photoperiods. 3. Plants that received low temperatures during their early development flowered more abundantly than those that received no low temperature. Ninety-eight per cent of one lot of seedlings that had received several weeks of cold weather during the spring flowered, ...