Yellow toadflax (Linaria vulgaris) - Bright yellow flowers with an orange throat and long spur. Linear leaves with a narrow stem.
Situation in Kansas
Yellow toadflax or "Butter and Eggs" is found in home gardens and landscapes. Sometimes cultivated plants escape and grow wild. Once established, this plant becomes difficult to control due to its large underground root and rhizome system. Several infestations are known in the eastern half of the state.