Memoirs of The New York Botanical Garden
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of Vascular Plants of Northeastern United States and adjacent Canada
Details: Viola x wittrockiana Gams
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Viola x wittrockiana Gams
- Originating by hybridization between V. tricolor and other spp. such as V. lutea Huds., and selected for large fls (5–10 cm wide) in diverse colors, occasionally escapes or persists briefly after cult.