During June and most of July, the apical meristem in the tulip bulb lays down the primordia of foliage leaves. Toward the end of July, or early in August, perianth primordia are initiated, followed rapidly by stamen and pistil primordia. The late Darwins lag behind the early classes in the initiation of floral organs. In view of slight variations of stage of development in each variety tested, and in view of possible effect of seasonal conditions, August first is suggested as an approximate critical date for floral initiation.
Proceedings of the Iowa Academy of Science
©1941 Iowa Academy of Science, Inc.
Sass, John E.
"The Critical Period for Floral Initiation in Tulipa (Abstract),"
Proceedings of the Iowa Academy of Science, 48(1), 196-196.
Available at: https://scholarworks.uni.edu/pias/vol48/iss1/31