Sorbus is treated here in the broad sense, including the subgenera Aria and Torminaria. However, these two subgenera are likely to be recognized at generic rank, based on flower and fruit characters, once molecular studies can consistently resolve their placement within the Pyrinae, overcoming current difficulties with interfertility, reticulate relationships, rapid radiation, and small samples[].
The taxonomy of Sorbus is complicated by apomixis, polyploidy, and hybridization among sections and genera, especially in Eurasia. Sorbus hybridizes with several other genera in the tribe Maleae, including Amelanchier (×Amelasorbus Rehder); Crataegus (×Crataegosorbus Makino); Aronia (×Sorbaronia C. K. Schneider); Cotoneaster (×Sorbocotoneaster Pojarkova); Pyrus (×Sorbopyrus C. K. Schneider), and Malus (×Tormimalus Holub [= Sorbus subg. Torminaria × Malus])[].

Common Name: American Mountain Ash

General Information

Sorbus americana is a deciduous shrub or a tree with a rounded canopy; it can grow from 4 - 10 metres tall. The plant usually produces 1 - 4 main stems[].
The tree is harvested from the wild for local use as a food, medicine and source of materials. It is sometimes grown as an ornamental.

Known Hazards

Although no specific information has been seen, the seed, and other parts of the plant, is likely to contain cyanogenic glycosides. When injested, these compounds break down in the digestive tract to release cyanide. Used in small quantities in both traditional and conventional medicine, this exceedingly poisonous compound has been shown to stimulate respiration, improve digestion, and promote a sense of well-being[]. It is also claimed by some to be of benefit in the treatment of cancer - though this claim has been largely refuted.
In larger concentrations, however, cyanide can cause gasping, weakness, excitement, pupil dilation, spasms, convulsions, coma and respiratory failure leading to death[].
The levels of toxin can be detected by the level of bitterness:- sweet almonds, for example, contain only very low levels of it and are safe to eat in quantity, whilst bitter almonds (which are used as a flavouring in foods such as marzipan) contain much higher levels and should only be eaten in very small quantities. Great caution should be employed if the taste is moderately to very bitter[].

Botanical References

, ,

Range

Eastern N. America - Minnesota and Ontario to Newfoundland, south to Tennessee and Georgia

Habitat

Cool, moist woods, lake and stream shores, rocky hillsides, thickets; at elevations up to 1,300 metres[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	6.00 m
Growth Rate	Slow
Pollinators	Insects
Cultivation Status	Ornamental, Wild

Cultivation Details

Sorbus americana is a very cold-hardy tree, tolerating temperatures down to around -40°c when dormant[].
Succeeds in most reasonably good soils in an open sunny position[]. Tolerates partial shade[], though it fruits better in a sunny position[]. Dislikes dry soils[]. Able to succeed in poor soils and to become established on exposed open ground[].
A slow-growing and relatively short-lived tree in the wild[], it fruits freely in Britain[].
Plants are susceptible to fireblight[].

Edible Uses

Fruit - raw or cooked[, ]. Rich in iron and vitamin C[, ]. The fruit is used mainly in making pies, preserves etc, but it can also be eaten raw after a frost because it turns sweeter then[, ]. The fruit has a high tannin content and so should only be used in moderation if eaten raw[]. It can also be dried and ground into a meal[]. The bright red to orange-red, globose to subglobose fruit is 4 - 8mm in diameter, produced in dense clusters[, ].

Medicinal

The inner bark has astringent and antiseptic properties[]. It is also used as a blood purifier and appetite stimulant[]. An infusion is used (sometimes with the terminal buds added) in the treatment of colds, debility, diarrhoea etc[, ]. When mixed with sweet flag (Acorus calamus) it is used as a tonic[].
A poultice of the burnt bark has been used in the treatment of boils[].

The fruit is antiscorbutic, diuretic, mildly laxative, astringent and digestive[, ]. It is an ideal accompaniment for foods that are hard to digest[].
A tea from the berries is antiscorbutic and astringent[, ]. It has been used as a rectal wash for piles[].
It is also used in homeopathic remedies[, ].

Other Uses

Wood - soft, light, close grained, with little strength[, , ]. It weighs about 34lb per cubic foot[] and is of no commercial value[].

Propagation

Seed - best sown as soon as it is ripe in a cold frame[, ]. If you have sufficient seed it can be sown in an outdoor seedbed[, ]. Stored seed germinates better if given 2 weeks warm then 14 - 16 weeks cold stratification[], so sow it as early in the year as possible. Prick out the seedlings into individual pots when they are large enough to handle. Seedlings are very slow to put on top-growth for their first year or two[], but they are busy building up a good root system. It is best to keep them in pots in a cold frame for their first winter and then plant them out into their permanent positions in late spring.