Also called Toadflax, these common roadside snapdragons are nearly as showy as their cultivated cousins. They bloom all summer, and they have no objection to a crack in the sidewalk if they can’t find posher quarters. Once placed in the family Scrophulariaceae, but now, thanks to these newfangled genetic studies, removed to the plantain family.
From Gray’s Manual of Botany: Linaria vulgaris Hill. (RAMSTED, BUTTER AND EGGS.) Glabrous, erect, 1.3 m. or less high; leaves pale, linear or nearly so, extremely numerous, subalternate ; raceme dense ; corolla 2-3 cm. long or more, including the slender subulate spur ; seeds winged. Fields and roadsides, throughout our range. (Nat. from Eu.)