Sour cherry blossoms, from Wikimedia Commons (Pro2).

Environment: The sour cherry tree grows best in cool and humid climates, such as the climates found in the eastern temperate regions of the United States.The sour cherry tree thrives in sandy and graveled soils that are not muddied and heavy from water flooding.

Shape: The sour cherry tree is small tree, typically growing from fifteen to twenty feet in height. The limbs are thin and tend to droop, causing a shrub-like appearance. The canopy is typically dense during the spring and summer seasons. 

Sour cherry drupes, from Wikimedia Commons (Roybb95).

Flowers: The sour cherry has individual white or pink flowers, like the sweet cherry, that consist of five petals. The flowers are inflorescence buds, meaning that the flowers are grouped in clusters by a stem on a branch. Sour cherries typically produce two to four inflorescence buds that have long pedicels, the individual stem of each flower that is attached to the main stem of the inflorescence. More than half of the sour cherry flowers arise from buds that grow on spurs, or short sub-twigs, while the rest of the flowers grow from axillary buds, or buds that develop at the intersection of the stem and the petiole. Sour cherry trees are self-fertile, meaning that they require no pollinators, and the seeds of the sour cherry tree, like all other cherry seeds, only germinate in the cold seasons and grow in the spring; an evolutionary mechanism to prevent seedlings from dying in cold weather.

Sour cherry leaves and fruit, from Wikimedia Commons (Maderibeyza).

 Fruit: The sour cherry fruit is a drupe, or a fleshy outer fruit that surrounds a hard layer, or endocarp, that contains a seed. The sour cherry drupe is edible and typically bright red in color, although may be dark red or purple. Sour cherry drupes have less color variation in comparison to the sweet cherry, prunus avium, and typically take two to three months to develop.

 Leaf: The sour cherry leaf is simple (one leaflet on the leaf stem) and alternate (the leaves are not attached across from each other and alternate along the branch). The leaf is thin and has an elliptic shape with serrated, or tooth-like, edges that are wider than they are high. Sour cherry leaves are dark green on the upper leaf surface, and pale green on the lower leaf surface and have pointed tips.

Bark: The bark for the young sour cherry grey-brown or red-brown with white spots, while the bark for the older sour cherry is dark red-brown and rough, and breaks into stiff scale-like layers.