In case of the annual, all structures die at the end of first season's growth. In the biennial only the aerial shoot dies at end of first season's growth. The root and the crown of the biennial prepare, during the first season, for the second season's growth which consists chiefly in the development and fruiting of the flowering shoots that are present on the crown but held in check during first season's growth.
Proceedings of the Iowa Academy of Science
©1930 Iowa Academy of Science, Inc.
Martin, J. N.
"The Anatomy of the Crowns and Roots of the Annual and Biennial White Sweet Clover Compared,"
Proceedings of the Iowa Academy of Science, 37(1), 209-210.
Available at: https://scholarworks.uni.edu/pias/vol37/iss1/32