a. Bot. [f. TRI- + Gr. ἀδελφός brother + -OUS, after DIADELPHOUS.] Of stamens: United by the filaments into three bundles. Of a plant: Having the stamens so united.
1830. Lindley, Nat. Syst. Bot., 87. Stamens [of the Pea tribe] … either distinct or monadelphous, or diadelphous; very seldom triadelphous.
1896. Henslow, Wild Flowers, 18. In the St. John’s worts, they [the filaments] are grouped into clusters … of three or five. These are therefore triadelphous and pentadelphous.
