Key to Wisconsin Prunus

• 1a.Inflorescences racemes, 12–20-flowered. 2

• 1b.Inflorescences corymbs or umbels, with 12 or fewer flowers. 3

• 2a.Leaves ovate or elliptic to lanceolate, broadest at or below the middle, glossy above, the margins with incurved or appressed teeth; sepals with margins usually entire, rarely with a few glandular teeth; hypanthia persistent. P. serotina

• 2b.Leaves elliptic to obovate, broadest at or above the middle, dull above, the margins with ascending to spreading teeth; sepals toothed, erose; hypanthia deciduous. P. virginiana

• 3a.Flowers and fruits sessile; ovary and fruit pubescent. 4

• 3b.Flowers and fruits pedicellate; ovary and fruit glabrous. 5

• 4a.Youngest twigs pubescent; leaves densely pubescent below; fresh fruit less than 1.5 mm in diameter, red. P. tomentosa

• 4b.Youngest twigs glabrous; leaves glabrous below, sometimes with a few hairs on the midveins; fresh fruit more than 1.5 mm in diameter, yellow to orange. P. persica

• 5a..Calyx lobes glabrous (or with glandular margins); fruit (cherries) not grooved, not glaucous, the pit round. 6

• 5b.Calyx lobes pubescent, at least at the base; fruit (plums) with a shallow groove, the pit somewhat flattened. 8

• 6a.Low, spreading shrubs with decumbent or ascending branches; leaves oblanceolate to obovate-elliptic, marginal teeth obscure or absent proximally; calyx lobes glandular. P. pumila

• 6b.Erect small trees or bushy shrubs; leaves ovate to obovate, toothed along the entire margin; calyx lobes eglandular. 7

• 7a.Inflorescence a corymbose-raceme with a central axis; petals glabrous; leaves broadly ovate, oblanceolate, or suborbiculate; fruit black. P.mahaleb

• 7b.Inflorescence umbellate (to corymbose); petals hairy on the outside near the base; leaves elliptic, oblong-lanceolate or lanceolate; fruit red. P. pensylvanica

• 8a.Leaf teeth sharp, glandless; calyx lobes eglandular. P. americana

• 8b.Leaf teeth gland-tipped or rounded; calyx lobes glandular. P. nigra