Amelanchier species are known by several different common names including serviceberry, Juneberry, and shadbush or shadblow, the latter two because their spring bloom coincides with shad returning to rivers along the Atlantic seaboard. Amelanchier is a member of the rose family (Rosaceae); taxonomic references differ on how many species are in the genus (thanks to frequent hybridization and genetic variability within species), but the majority of the 20 or so species are native to North America.
Amelanchier species [pdf] vary in habit from thicket-forming shrubs to single or multi-stemmed small trees. Cultivars of small-tree species, especially downy seviceberry (A. arborea) [pdf], Allegheny serviceberry (A. laevis), and hybrids of the two (A. x grandiflora), are readily available at nurseries and make excellent additions to the landscape.
Serviceberries put on a showy though fairly short-lived display of white flowers in early to mid spring before or with foliage emergence. The one-quarter- to one-half-inch diameter fruits mature from green to red to deep blue purple and are readily eaten by many bird species including robins, bluebirds, cedar waxwings, catbirds, and mockingbirds. To human taste, serviceberry fruits can vary from insipid to delicious, depending on species and individual plant. Some people prefer a good serviceberry to a blueberry (just be prepared for the small, crunchy seeds in serviceberries). Saskatoon, or western serviceberry (A. alnifolia), is cultivated commercially for fruit production in the western U.S. and parts of Canada.
Fun fact: The “berry” in serviceberry is a bit of a misnomer, since Amelanchier fruits are pomes [pdf] (as are apples, pears, and firethorn [Pyracantha] fruits) rather than true botanical berries (like grapes, gooseberries [Ribes], and, believe it or not, tomatoes).