This species is distinguished from Johnny Jump-up (Viola pedunculata, see above) by its paler lemon-yellow, slightly smaller flowers (the lowest petal being 6–16 mm long). Like Johnny Jump-up, the face of the petals has dark brown veins at the base of the lowest petal, and reddish-brown patches on the back of the upper petals. A more important difference is that this species has basal leaves. The basal and cauline leaves are different from each other. Basal leaves are generally green, glabrous, sometimes shiny above, sometimes purplish below, roundish with a tapered base, and acute or obtuse tip. Cauline leaves are lanceolate to triangular, with a heart-shaped, truncate or tapered base, and acute tip.
Note: Viola purpurea is a notoriously difficult species. Differentiating between the subspecies is challenging even for experts.