Viola nuttallii Pursh
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Finely hairy to subglabrous, with numerous ascending stems to 1(–1.5) dm from a stout, deep-seated rhizome; stems bearing lvs and fls from near the base; lf- blades mostly lanceolate or lance-elliptic, varying to sometimes lance-ovate, 2–6 cm, tapering (seldom more abruptly contracted) to petioles nearly or quite as long, mostly (2–)2.5–6 times as long as wide; fls 1–1.5 cm wide, the pet yellow, with brown-purple lines near the base and often purplish-tinged outside, the lateral pet beardless or slightly bearded; style-head bearded; frs subglobose or ellipsoid, 6–8 mm; 2n=24. Prairies and plains; widespread in the w. cordillera and e. onto the Great Plains, reaching Kans., Nebr., S.D., and w. Minn. Apr.–July. The plains plants, as here described, are var. nuttallii. Several other vars., differing in ploidy-level and in form, size, and vestiture of the lvs, occur farther w.
yellow prairie violet