amentaceous,a.Bot.|æmənˈteɪʃəs| [f. L. amentum + -aceous.] a. Of the nature of a catkin. b. Bearing catkins. c1737Miller (J.) The pine tree hath amentaceous flowers or katkins.1852T. Ross Humboldt's Trav. I. vi. 213 Among amentaceous plants, the willows, oaks, and birch-trees.