Villous throughout; stems slender, to 6 dm, with many branches from the base and few distally; petioles 2-6 mm; lvs broadly round-ovate, the larger 2-3 cm, entire, rounded or cordate at base; pedicels 5-20 mm, villous; cor 6-8 mm, yellow, the upper lip purple within; spur decurved, 5 mm. Native of the Mediterranean reg., established as a weed in moist sandy soil in most of our range, s. to Fla. June-Sept. (Linaria s.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.