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:

General Information

Sorbus japonica is a deciduous tree that can grow up to 20 metres tall, though often only half that size in cultivation[].
The tree is harvested from the wild for local use as a food and source of materials.

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

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Range

E. Asia - central and southern Japan, Korea.

Habitat

Hills and mountains[].

Properties

Edibility Rating
Other Uses Rating
Habit	Deciduous Tree
Height	12.00 m
Pollinators	Insects
Cultivation Status	Wild

Cultivation Details

Sorbus japonica is a moderately cold-hardy tree, tolerating temperatures down to around -20°c when dormant. However, it requires hot summers if it is to thrive and will often fail to do well in regions with cool summers, even if the winters are mild.
Succeeds in most reasonably good soils in an open sunny position[]. Tolerates light shade[], though it fruits better in a sunny position[].
Plants are susceptible to fireblight[].

Edible Uses

Fruit - raw or cooked. The fruit is up to 13mm across[] and is produced in bunches which makes harvesting easier[].

Medicinal

None known

Other Uses

We have no specific information for this species, but the wood of Sorbus species in general is hard, heavy, and fine-grained, and is suitable for making furniture or small, carved articles[].

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.