Dalmatian toadflax, Linaria dalmatica (L.) Mill., and yellow toadflax, Linaria vulgaris Mill., are exotic weeds of rangeland, grassland, forests, and cropland. Both Dalmatian and yellow toadflax are short-lived perennial forbs that are easily recognized by their yellow snapdragon- like flowers (Figure 1a, 1b). Both species propagate by seed and vegetatively from shoots that arise either from lateral rhizomes (Dalmatian toadflax) or from buds developing on their roots (yellow toadflax). Dalmatian toadflax is native to southeastern Europe while yellow toadflax is considered to be native to Europe and Asia. Hybrids of Dalmatian and yellow toadflax have been found throughout northwestern USA (Figure 1c; hybrids are discussed further in Chapter 2 of this manual). Although several exotic toadflax species have been intentionally or accidentally introduced to North America, these two species and their hybrids are by far the most common and problematic for land managers, and are the focus of this manual. The use of "toadflaxes" throughout this manual encompasses both Dalmatian and yellow toadflax, as well as their hybrids.
Sing, Sharlene E.; De Clerck-Floate, Rosemarie; Hansen, Richard W.; Pearce, Hal; Randall, Carol Bell; Tosevski, Ivo; Ward, Sarah M. 2016. Biology and biological control of Dalmatian and yellow toadflax. FHTET-2016-01. Morgantown, WV: U.S. Department of Agriculture, Forest Service, Forest Health Technology Enterprise Team. 141 p.