The dogwood was adopted as Missouri’s state tree on June 20, 1955. I’ve never learned any details of its adoption, but the dogwood is one of the most popular state trees and state flowers in the eastern United States.
State arboreal emblem.
10.040. The flowering dogwood scientifically designated as Cornus Florida L. is declared to be the arboreal emblem of Missouri and the state department of agriculture shall recognize it as the official state tree and encourage its cultivation on account of the beauty of its flower and foliage.
(L. 1955 p. 769 § 1, A.L. 1957 p. 726)