Pterocarya rhoifolia aka Japanese Wingnut

Pterocarya rhoifolia, or Japanese wingnut, is a deciduous tree. It belongs to Juglandaceae, the walnut family. Its native range covers Japan, South Korea, and eastern Shandong, China. It grows in temperate regions and loses its leaves each year. In Japan, it grows in valleys and mountain areas. In China, it grows beside rivers and mountain streams. These habitats point to its need for moist ground.

This is a large tree, reaching about 98 feet [30 metres]. Its size suits the canopy layer of a woodland garden. Allow room for a tree of this scale when planting. The leaves give off a scent when bruised. The supplied species evidence gives no further leaf or bark details. Flowers appear in June. Each tree carries separate male and female flowers. Wind moves pollen between them. Seeds ripen from October through December.

Choose a sunny site with plenty of moisture at the roots. PFAF states that this species cannot grow in shade. It favours rich loam, though clay soil is also suitable. It accepts mildly acid, neutral, and mildly alkaline ground. PFAF lists USDA hardiness zones 5–9. It also warns against long winter spells below about 10°F [−12°C]. Frost can damage young plants and new shoots on older trees. These cautions matter when choosing a site in colder areas.

Seeds offer one way to raise new trees. Sow fresh seed in a cold frame once ripe. Stored seed needs a warm-water soak lasting 24 hours. Follow this with two to three months of cold treatment. Keep seedlings under glass during their first winter. Plant them out in late spring or early summer. Other methods include layering and dividing suckers while dormant. Cuttings can use half-ripe wood in summer or mature shoots in November.

PFAF lists the seeds as edible but gives few details. Their small size makes them awkward to use. It reports no known hazards, but this is not proof of safety. It lists no known medicinal uses. The light, soft wood resists cracking and has practical uses. These include making clogs and chopsticks. PFAF does not flag this species as weedy. The supplied evidence names no species-specific pests or diseases.