Broussonetia kazinoki aka Hanji

Broussonetia kazinoki, or kozo, belongs to the mulberry family, Moraceae. It grows in East Asia, including China, Japan, and Korea. Plants For A Future also lists Taiwan within its range. It grows at forest edges and on low mountains. It also occurs near homes. Kew describes its origin as involving native and naturalised parents. This makes its native range less clear than distribution lists suggest.

Kozo forms a small tree or shrub with an open, spreading crown. It sheds its leaves each year. Useful Tropical Plants gives heights of 6.6–13 feet [2–4 metres]. Plants For A Future reports up to 15 feet [4.5 metres]. Its bark provides fibre, the main reason people grow it. Growers in Japan cut plants back each year for this crop. The fibre goes into paper, cloth, and rope.

Plants For A Future lists flowering in August and ripe seed in September. Some plants bear both male and female flowers. Others carry just one sex on each plant. The sources report that kozo does not set seed through self-fertilisation. Growers usually need male and female plants for seed. The fruit forms a small ball with edible parts projecting outward. It tastes sweet but offers little flesh.

Grow kozo in a warm spot with full sun. It suits a sunny woodland edge rather than deep shade. It accepts sand, loam, or clay if water drains well. It also grows in poor sandy or gravelly ground. Its soil range spans mildly acid to mildly alkaline conditions. It accepts dry or moist soil and tolerates air pollution. Plants For A Future lists USDA zones 6–9. New spring shoots can suffer frost damage, even on older plants. A site shaded from early morning sun helps protect this growth.

People eat the fruit raw and cook the leaves as greens. Sources also list the flowers as edible, without preparation details. Both main use sources list no known hazards. Yet Plants For A Future reports a caution about prolonged fruit use. It says this may weaken bones, so safety claims need care. Traditional uses include fruit tonics for sight and sexual potency. These reports do not establish medical benefit. The supplied sources name no specific pests or diseases. Plants For A Future does not flag kozo as weedy.