Another European plant, is sparingly intr. in some of our coastal states. It is intermediate between nos. 3 [Rorippa sylvestris (L.) Besser] and 5 [Rorippa amphibia (L.) Besser], and is thought to be an unstable segregating series of hybrid origin. It differs from no. 5 in its solid stems and more pinnatifid lvs, and from no. 3 in its smaller frs (5-6 mm) and sessile or subsessile, less cleft (or subentire) upper lvs.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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