Primula

1. Leaves all or mostly 12–30 cm long; plant ca. 25–50 (or more) cm tall; flowers ca. 2–3 cm long, including stamens in a cone-like assemblage and reflexed corolla lobes.

P. meadia

1. Leaves (or blades if a petiole is present) less than 10 cm long; plants often shorter; flowers less than 1 (–2.5) cm long, with corolla lobes spreading but not reflexed.

2. Scape and leaves glabrous or farinose; flowers less than 1 cm long, the corolla pale to deep magenta with yellow “eye;” leaves tapered at base but without distinct petiole; style ca. 1–3.5 mm long; plant native in calcareous habitats.

P. mistassinica

2. Scapes and leaves (especially beneath) pubescent; flowers ca. 1.5–2.5 cm long, the corolla yellow or purplish; leaves mostly contracted to a distinct winged petiole; style much exceeding 3.5 mm (ca. 5–10 mm); plant rarely escaped from cultivation.

P. veris

All species found in Primula

Primula meadiaSHOOTING-STAR 
Primula mistassinicaBIRD'S-EYE PRIMROSE 
Primula verisCOWSLIP 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. April 28, 2017. http://michiganflora.net/genus.aspx?id=Primula.