The genus Salix, as recognised in 2019, is comprised of probably more than 300 distinct species (over 500 if you also accept hybrid species). Many of these species are very similar, sometimes being separated as much by native range as by any other characteristic. Hybridization between species is common, when this is coupled with the high genetic and morphological variability within many species, and different levels of ploidy, the complexity of this genus is clear.
Misidentification of specimens is not rare, even amongst botanists, and many records of plant use will often equally apply to one or more related species that were not seen as distinct when the report was made. Equally, several species not included in the database will be found to have a range of these uses. In general, all species in the genus have medicinal uses, especially as antiinflammatories, analgesics and febrifuges, they can all serve as emergency foods, many of them have flexible stems and can be used in basket making, and many of them can be planted in moist to wet conditions in order to stabilize the soil and improve wildlife habitats.

Common Name:

General Information

Salix japonica is a deciduous shrub with slender branches; it can grow up to 2 metres tall[]..
The plant is harvested from the wild for local use as a food and medicine. It is sometimes grown as an ornamental.

Known Hazards

None known

Botanical References

,

Range

E. Asia - central Japan.

Habitat

Hills and mountains[].

Properties

Edibility Rating
Medicinal Rating
Habit	Deciduous Shrub
Height	1.50 m
Pollinators	Bees, Insects
Self-fertile	No
Cultivation Status	Ornamental, Wild

Cultivation Details

Salix species generally require an open position and abhor dryness at the roots. Whilst many can be found in wet or boggy soils, and prefer a damp, heavy soil, most will grow well in a range of moist but well-drained soils so long as they are fairly deep. Very few are at home in chalky soils[, , ].
The flowers are dioecious, male and female flowers being produced on separate plants. If seed is required then at least one plant of each sex need to be growing in reasonable proximity[].
Hybridization in the genus is common, especially when species are brought together in cultivation[].
Salix species are unusual in as much as, although they produce their flowers in catkins, these are insect rather than wind pollinated. Indeed, the flowers of many species are excellent sources of nectar for bees and other insects, especially valuable are those species that flower early in the growing season[].
The roots of Salix species are often vigorous and extensive and can range some distance from the plant. Several species are known to cause problems by growing into drains and drainage systems as their roots seek out moisture[].
Species in this genus are often notably susceptible to honey fungus[].

Edible Uses

Young shoots and flower buds - cooked[, ]. Not very palatable[].

Growing in harsh and difficult environments, as many willows do (they can be found within the arctic circle, on mountains and even in the desert), Salix species have often been utilized as an emergency food source. They are, indeed, often a highly favoured food source for birds and mammals and, whilst few species would lay claim to culinary excellence for humans, the young shoots and inner bark are both edible eaten either raw or cooked[].
We have no specific information for this species, but the inner bark can be eaten fresh or it can be dried, ground into a powder and then added to cereal flour for use in making bread etc. It has a very bitter flavour, The young shoots are also somewhat bitter and not very appetizing - unless you are really hungry of course![].

Medicinal

The bark, twigs, leaves, leaf buds, and flower buds of all Salix species contain phenolic glycosides, particularly salicin and salicortin (which breaks down when the plant material is damaged to produce salicin). The quantity of these compounds can vary greatly between species, and even within geographical races of the same species. Taste is a simple test to ascertain levels of these compounds - the more bitter the flavour, the more compounds it contains[].
Salicin has several valuable medicinal properties. In particular it is an effective antiinflammatory and pain reliever, and is also a valuable febrifuge[].
Modern medicine has used salicin as a pathway to producing the common pain reliever aspirin and, until a totally synthetic pathway of producing the medicine was discovered, several Salix species were harvested on a commercial basis to obtain salicin.
Many Salix species have a history of traditional use (not always documented). All parts of the plant can be used, but the bark is more commonly employed. Their pain-relieving and antiinflammatory properties make them useful in the treatment of verious conditions including headaches, neuralgia and joint pains, whilst they can also be very helpful in the treatment of fevers[, ].

Other Uses

None known

Propagation

Willow seed is very small and light, and has a very short viability, perhaps as little as a few days in some species. It must be surface sown as soon as it is ripe. In nature the seed only germinates in disturbed soils in an open situation. In nursery conditions, sow the seed in a tray in a moderately sunny position and keep the soil moist. Germination is usually quite rapid - prick out the seedlings into individual pots when they are large enough to handle and grow on until large enough to plant out. Plants generally establish better if planted out whilst quite small.
Cuttings of mature wood of the current year's growth or older can root at almost any time of the year, though late autumn is considered best as this produces a better balance of root and stem growth the following spring[]. Plant them in a sheltered outdoor nursery bed or straight into their permanent position and give them a good weed-suppressing mulch. Most species are very easy. Plant into their permanent positions in the following autumn.
Cuttings of half-ripe wood, early to mid summer in a frame. Very easy.