Correspondence 1 indicates that George Argus (The Jepson Manual [Ed. 1] author for Salix), in Madroño 44: 123 (1997), lists Salix bonplandiana var. laevigata in synonymy under Salix laevigata, the basionym specified by Dorn.
Correspondence 2 confirms that Salix bonplandiana Kunth var. laevigata (Bebb) Dorn is to be treated as a synonym of Salix laevigata Bebb in The Jepson Manual [Ed. 2].