That one of two whorls is often retarded developmentally in diplostemonous flowers has been illustrated (see Ronse Decraene, 1992; Ronse Decraene & Smets, 1995a, 1998; Walker-Larsen & Harder, 2000).
Indeed, the acceptance of the nectarial stubs as staminodes involves the acceptance of ancestral polyandry in Greyiaceae and Francoaceae, where the related rosid families are all basically diplostemonous.
Theophrastaceae, Sapotaceae, Myrsinaceae, and Primulaceae are examples of the derivation of the obhaplostemonous androecium from diplostemonous ancestors.
In this way a diplostemonous androecium becomes transformed into an (ob)haplo-stemonous one.
The association of Clusiaceae with clades having diplostemonous flowers (e.