During a study of the histological effects of 2, 4-D on sunflower, root-like outgrowths were observed frequently on leaves and cotyledons. Protuberances on bean leaves treated with 2, 4-D have been reported by Felber (Felber, 1948). Felber describes these outgrowths as "thorn-like," 1 to 3 mm. long, white in color, and covered with small hairs. The root-like nature of the protuberances formed on sunflower suggest that they are different, structurally, from those observed on bean leaves. Cotyledonary roots induced by 2, 4-D have been described by Akamine (Akamine, 1948). This production of cotyledonary roots is obviously the same phenomenon as cotyledonary roots described in the present paper. A common occurrence ascribed to the influence of growth substances is organ building, usually manifested in the development of root primordia (Bausor et. al., 1940). Such organs may be induced in leaves as well as in other parts of the plant. The present paper describes their occurrence on sunflower leaves and the conditions under which they develop. The protuberances on sunflower are definitely root-like in appearance and structure and for these reasons will be referred to in this paper as "roots."
Proceedings of the Iowa Academy of Science
©1949 Iowa Academy of Science, Inc.
Postlethwait, S. N.
"Root-Like Protuberances Formed on Leaves and Cotyledons of Helianthus Annuus L. in Response to 2, 4-D Treatment,"
Proceedings of the Iowa Academy of Science, 56(1), 161-166.
Available at: https://scholarworks.uni.edu/pias/vol56/iss1/23