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Key to Species — Part 26

A. Flowers axillary, in sessile umbels; fruit with oval, flattened stone.

Plums

B. Fruit red or yellow, without bloom.

C. Leaves broadly elliptical, taper pointed, dull green, thick; twigs thorny.

D. Petioles bearing 2 glands near base of leaf; pit much compressed.

(P. nigra) CANADA PLUM

DD. Petioles without glands, pit thick.

(P. Americana) WILD RED PLUM

CC. Leaves broadly oval, finely serrate, leathery; pit grooved at back.

(P. subcordata) PACIFIC PLUM

CCC. Leaves lanceolate, thin shining; petioles glandular; pit thick.

D. Twigs stout, stiff, usually thornless; leaves broad; fruit thick skinned.

(P. hortulana) WILD-GOOSE PLUM

DD. Twigs slender, supple, thorny; leaves narrow; fruit thin skinned.

(P. angustifolia) CHICKASAW PLUM

BB. Fruit blue or black, with pale bloom, small.

C. Petioles not glandular at apex.

D. Leaves lanceolate to ovate, long pointed.

(P. Alleghaniensis) ALLEGHANY SLOE

DD. Leaves oblong or obovate, blunt pointed.

(P. umbellata) BLACK SLOE

AA. Flowers axillary, in umbels; fruit small, red, shining, globular.

Bird Cherries

B. Leaves lanceolate, taper pointed; fruit sour.

(P. Pennsylvanica) WILD RED CHERRY

BB. Leaves obovate, blunt pointed; fruit bitter.

(P. emarginata) BITTER CHERRY

AAA. Flowers in terminal racemes; fruit globose.

Wild Cherries

B. Trees small, blooming early; leaves broad, abruptly pointed.

C. Fruit red, puckery; sap rank smelling.

(P. Virginiana) CHOKE CHERRY

CC. Fruit purple, mild, edible.

(P. demissa) WESTERN CHOKE CHERRY

BB. Trees large, blooming late, leaves oval to lanceolate, taper pointed; fruit black, sweetish.

(P. serotina) WILD BLACK CHERRY

AAAA. Flowers in lateral racemes; leaves persistent; fruit globular.

Cherry Laurels

B. Fruit thin fleshed, dry.

C. Flowers in autumn; fruit brown.

(P. sphaerocarpa) WEST-INDIAN CHERRY

CC. Flowers in spring; fruit black; leaves with entire margins.

(P. Caroliniana) CHERRY LAUREL

BB. Fruit thick fleshed, juicy; leaves ovate, entire, or obscurely spiny serrate.

(P. integrifolia) ENTIRE-LEAF CHERRY

The genus Prunus includes trees with stone fruits, and has its representatives well distributed over the Northern Hemisphere. In its wild forms it is not as well known, perhaps, as in those varieties that horticulture has brought to high perfection and importance as fruit trees. There are over one hundred species, including many shrubby ones. Of this number about thirty occur in North America, only half of which assume tree form. All of these but the wild black cherry are small trees. Nevertheless the wood of most of them is valuable, being close grained and durable. Their fruits furnish food and medicinal substances. Beside the cherries and plums of others countries, the peach, apricot and almond belong to this genus. Important flowering varieties of each are to be added to this list of valuable introduced stone fruits.