Rubus coreanus aka Korean Blackberry

Rubus coreanus, or Korean bramble, is a deciduous shrub in the rose family. Its native range runs from northern and eastern China to Korea. It grows in temperate regions, forming part of thickets on slopes. It also grows in mountain valleys, along riverbanks, and beside roads. Records place it across a broad range of elevations. These extend from about 328 feet [100 metres] to 10,171 feet [3,100 metres].

In gardens, this shrub reaches about 10 feet [3 metres] tall and wide. Its rootstock lives for many years, but each stem lasts two years. The plant sends up new stems each year. Those stems bear fruit in their second year, then die. This cycle renews the growth while keeping the rootstock alive. It loses its leaves for winter. The supplied species account gives no further leaf or bark details.

Flowers open from July to August. Each flower has both male and female organs. Insects carry pollen between the flowers. Seeds ripen from August through October. The small fruits turn dark red or purple-black. They measure about 0.2–0.3 inches across. People can eat them raw or cook them. However, the cited account rates their flavour poorly. It notes limited cultivation for fruit in Japan. The fruit also yields a purple or muted blue dye.

Grow Korean bramble in moist soil that drains well. A good loam suits it, though it also accepts sand and clay. It tolerates mildly acid, neutral, and mildly alkaline soils. Choose full sun or partial shade, such as a woodland edge. The source describes it as easy to grow under these conditions. It lists USDA hardiness zones 5–9. Seed needs a cold period before it will sprout. Growers can also divide suckers in spring or near autumn leaf fall.

Traditional medicine uses the fruit, seeds, leaves, and roots. The source records fruit use for urinary and reproductive complaints. It also records leaf juice and root preparations for eye complaints. These are reports of traditional use, not proof of treatment benefits. The account lists no known hazards, but gives no detailed safety assessment. It reports no weed potential. The supplied evidence names no pest or disease problem specific to this species.