Woody climber, the younger branches usually pubescent and often glandular; lvs all separate, glabrous, elliptic to obovate, acute or obtuse, or the uppermost broadly ovate and acuminate; whorls of fls aggregated into a capitate cluster, the bractlets glandular; cor pale yellow, 3-5 cm, the tube glandular, longer than the lips; 2n=18, 36, 54. Native of Europe, n. Afr., and w. Asia, sometimes escaped from cult., especially eastward.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.