Oplopanax japonicus

Oplopanax japonicus is a shrub from Japan that sheds its leaves. It belongs to the Araliaceae family. It grows in climates with mild heat and cold. In the wild, it grows in damp woods and on stream banks. These sites often have rich soil. Plants For A Future gives its height as about 10 feet [3 metres]. The source does not say how wide this species grows.

The plant has many sharp spines that can irritate skin. Bear these in mind when choosing a site or handling stems. The shrub blooms in June. Each flower has both male and female organs. The supplied evidence gives no flower colour or facts about fruit. It gives no leaf shape or details of the bark. Older works classed this plant as part of Oplopanax horridus. Plants For A Future notes that later works treat it as a separate species.

This shrub needs cool soil that stays moist. It grows in sand, loam, or clay. Soil can be slightly acid, neutral, or slightly alkaline. Plants For A Future lists both light and full shade. Yet its notes on garden sites warn against deep shade. Damp woods or a shaded garden edge suit its stated needs. The source says it can cope with coastal exposure. It lists USDA zones 5–9. It also reports survival down to at least −15°C. Late spring frosts can still harm young shoots. Though it withstands winter cold, avoid frost pockets.

Its main garden use is for its form in woodland. Its spines limit where gardeners can place and handle it. Plants For A Future lists leaves, roots, and shoots as edible. Its notes on how to prepare them cover fewer parts. They cover only roots and very young shoots. They say to peel and cook the shoots. They also describe chewing roots once peeled. The source confirms that spines irritate skin. It also warns about calcium oxalate. But it lacks proof of that risk in this species. The evidence thus does not show that eating it raw is safe. Reports describe healing uses for root bark and stems, including pain relief. These reports do not prove health benefits or safe doses.

Gardeners can grow plants from seed sown in autumn. Plants For A Future says to use a cold frame for fresh seed. It says to shelter seedlings through their first winter. Plant them out after the last expected frost. Gardeners can also split off suckers while they are dormant. Taking root cuttings in winter is a further way to grow plants. The supplied evidence names no specific pests or diseases.