Common Name: Japanese Barberry

General Information

Berberis thunbergii is a spiny, compact, deciduous shrub, much branched from the base, and usually growing no more than 100cm tall[], though cultivated plants up to 300cm tall are recorded[, ]. Plants produce suckers and often form thickets in the wild[].
This is one of the most commonly cultivated ornamental barberries, with a range of cultivars suitable for purposes such as a ground cover and hedging[, ]. The bark has a range of medicinal uses and the fruit is supposedly edible, but very poor fare.
Widely grown as an ornamental, the plant can escape from cultivation and has become naturalized in some areas. It is considered a noxious weed in parts of N. America[]. The plant can invade a variety of habitats from damp lowlands to dry roadsides and waste places. This species forms dense stands in a variety of these habitats, including closed canopy forests and open woodlands, wetlands, pastures and meadows. Berberis thunbergii is highly shade-tolerant and displaces a variety of native herb and shrub species in areas where it becomes well established[].

Known Hazards

All parts of the plant contain the alkaloid berberine - this is most concentrated in the roots, stems and inner bark, and least concentrated in the fruits. In small quantities berberine has a range of effective medicinal applications but, in excess, can cause vomiting, lowered blood pressure, reduced heart rate, lethargy, and other ill-effects.
The fruit of most, if not all, members of this genus are more or less edible and can be eaten in quantity since the levels of berberine in the fruit are very low.

Botanical References

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Range

E. Asia - C. and S. Japan

Habitat

Naturalized in woods, old fields, roadsides; at elevations up to 1,300 metres in N. America[].

Properties

Weed Potential	Yes
Edibility Rating
Medicinal Rating
Habit	Deciduous Shrub
Height	2.00 m
Growth Rate	Medium
Pollinators	Insects
Self-fertile	Yes
Cultivation Status	Ornamental, Wild

Cultivation Details

Berberis thunbergii, when becoming naturalized outside of its native range, has shown a preference for areas where average maximum summer temperatures are in the region 21 - 25°c and average minimum winter temperatures range from -3 to -11°c[]. Dormant plants are able to tolerate temperatures down to about -25°c[].
An easily grown plant, it prefers a warm moist loamy soil but it is by no means fastidious, succeeding in thin, dry and shallow soils[, ]. Prefers a lime-free soil according to one report[]. Grows well in heavy clay soils. Succeeds in full sun or light shade[, ]. Tolerant of heavy shade[].
A commonly grown ornamental plant, there are many named varieties[].
Plants can be pruned back quite severely, they resprout well from the base[].
Unlike most other members of this genus, this plant does not usually hybridize with other species[].
This species is notably resistant to honey fungus[].
Some Berberis species (especially Berberis vulgaris) harbour the black stem-rust fungus (Puccinia graminis Persoon). This is a major disease of wheat and barley crops and can spread from infected barberries to the grain crop. The sale or transport of susceptible or untested species of Berberis is illegal in the United States and Canada[]. The U.S. Department of Agriculture lists Berberis thunbergii as resistant to infection by Puccinia graminis , and the species is widely grown as an ornamental in the United States. Preliminary tests carried out by Agriculture Canada, however, suggest that some strains may be susceptible to Puccinia graminis infection, and cultivation of Berberis thunbergii is illegal in Canada[].

Edible Uses

Fruit - raw or cooked[, ]. Dry with a very poor flavour[]. The fruits are about 8mm long and 4mm wide[, ].

Leaves - cooked.

Medicinal

The root bark is anthelmintic, antiseptic and febrifuge[].

The alkaloid berberine, which is universally present in the roots and stems of Berberis species, has marked antibacterial effects. Since it is not appreciably absorbed by the body, it is used orally in the treatment of various enteric infections, especially bacterial dysentery[].
It should not be used in combination with Glycyrrhiza species (Liquorice) because this nullifies the effects of the berberine[].
Berberine has also shown antitumour activity[].

Agroforestry Uses:

Plants can be grown as a medium-size hedge[]. They are very tolerant of trimming and have prickles which make them an effective barrier to larger creatures[].
The cultivar 'Atropurpurea Nana' can be used for ground cover[]. It makes a dense covering when planted 30cm apart each way[].
The plant is tolerant of poor soil conditions and is recommended for use in strip-mine reclamation projects[].

Other Uses

A yellow dye is obtained from the root and branches[].

Propagation

Seed - best sown as soon as it is ripe in a cold frame, when it should germinate in late winter or early spring[]. Seed from over-ripe fruit will take longer to germinate[], whilst stored seed may require cold stratification and should be sown in a cold frame as early in the year as possible[]. The seedlings are subject to damping off, so should be kept well ventilated[]. When the seedlings are large enough to handle, prick them out into individual pots and grow them on in a cold frame. If growth is sufficient, it can be possible to plant them out into their permanent positions in the autumn, but generally it is best to leave them in the cold frame for the winter and plant them out in late spring or early summer of the following year.
Cuttings of half-ripe wood, mid summer in a frame. Fairly easy[].
Cuttings of mature wood of the current season's growth, preferably with a heel, autumn in a frame[]. Fairly easy[]
Layering
Division of suckers