Suffruticose, ±glandular-pubescent plants, prostrate or creeping, 3-6 dm, the branches often ending in weak thorns; stipules about as long as the petiole; lfls 3, or only 1 when subtending fls, elliptic-oblong to oval, 1-2 cm; fls pale red, 1-2 cm; 2n=30. Native of w. Europe, occasionally adventive in waste places about eastern cities. May-Sept. (O. spinosa, misapplied)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.