Saskatoon

It is a deciduous shrub or small tree that most often grows to 1–8 metres (3–26 feet), rarely to 10 m or 33 ft, in height. Its growth form spans from suckering and forming colonies to clumped. The leaves are oval to nearly circular, 2–5 centimetres (3⁄4–2 inches) long and 1–4.5 cm (1⁄2–1+3⁄4 in) broad, on a 0.5–2 cm (1⁄4–3⁄4 in) leaf stem, with margins toothed mostly above the middle. As with all species in the genus Amelanchier, the flowers are white, with five quite separate petals and five sepals. In A. alnifolia, they are about 2.5–5 cm (1–2 in) across, with 20 stamens and five styles, appearing on short racemes of 3–20, somewhat crowded together, blooming from April to July. The fruit is a small purple pome 5–15 mm (3⁄16–19⁄32 in) in diameter, ripening in early summer. It has a waxy bloom. Saskatoon species can be relatively difficult to distinguish.

Chemistry. Saskatoons have total polyphenol content of 452 milligrams per 100 grams (average of 'Smoky' and 'Northline' cultivars), flavonols (61 mg) and anthocyanins (178 mg), although others have found the phenolic values to be either lower in the 'Smoky' cultivar or higher. Quercetin, cyanidin, delphinidin, pelargonidin, petunidin, peonidin, and malvidin were present in saskatoon berries.

The plant is present from Alaska across most of western Canada and in the western and north-central United States. It grows from sea level in the north of the range, up to 2,600 m (8,530 ft) elevation in California and 3,400 m (11,200 ft) in the Rocky Mountains. It is a common shrub in the forest understory, as well as canyons.

A. alnifolia is susceptible to cedar-apple rust, Entomosporium leaf spot, fireblight, brown rot, Cytospora canker, powdery mildew, and blackleaf. Problem insects include aphids, thrips, mites, bud moths, saskatoon sawflies, and pear slug sawflies. It is also a larval host to the pale tiger swallowtail, two-tailed swallowtail, and the western tiger swallowtail. The foliage is browsed by deer, elk, rabbits, and livestock. The fruit are eaten by wildlife including birds, squirrels, and bears.

Saskatoon berries contain significant amounts of total dietary fiber, riboflavin and biotin, and the dietary minerals, iron and manganese, a nutrient profile similar to the content of blueberries.

Seedlings are planted with 4.0–6.1 m (13–20 ft) between rows and 0.46–0.91 m (1.5–3 ft) between plants. An individual bush may bear fruit 30 or more years. Saskatoons are adaptable to most soil types with exception of poorly drained or heavy clay soils lacking organic matter. Shallow soils should be avoided, especially if the water table is high or erratic. Winter hardiness is exceptional, but frost can damage blooms as late as May. Large amounts of sunshine are needed for fruit ripening.

The name saskatoon derives from the Cree inanimate noun ᒥᓵᐢᐠᐘᑑᒥᓇ misâskwatômina (ᒥᓵᐢᐠᐘᑑᒥᐣ misâskwatômin NI sg, 'saskatoonberry', misâskwatômina NI pl 'saskatoonberries'). The specific epithet alnifolia is a feminine adjective. It is a compound of the Latin word for "alder", alnus, and the word for "leaf", folium. Historically, it was also called pigeon berry. "Service berry" appears to be a name applied by European immigrants who found it similar in appearance to the European "service tree" plants of genus Sorbus and Cormus.