• (a.) Of or pertaining to the class Diadelphia; having the stamens united into two bodies by their filaments (said of a plant or flower); grouped into two bundles or sets by coalescence of the filaments (said of stamens).
Having the stamens United into two groups, or all but one united in a group and one free. ... (09 Oct 1997) ... 
Describing stamens that are united by their filaments in two clusters, as in many legumes which have 9 stamens fused and one separate.
In two groups, as the stamens of some Leguminosae, joined by their filaments.
diadelphous A description of stamens or flowers that have the stamen filaments grouped into two bundles or groups.
(of stamens) united into two sets by their filaments. · (of plants) having the stamens so united.