Asarum nipponicum

Asarum nipponicum is a small plant that lives for years. It comes from temperate Japan and belongs to the Aristolochiaceae family. Kew gives Honshu as its native range. Plants For A Future includes Shikoku as well. The RHS lists it as non-native to Britain and Ireland. The sources say little about its home in the wild. Much about how it grows in gardens also remains unclear.

Plants For A Future gives a height of about 0.33 feet [0.1 metres]. It is thus a low plant for use in shade. The species account does not give its full-grown spread. Nor does it describe the leaves, stems, or fruit. Each flower has both male and female organs. Flies carry pollen for the plant, the account says. It gives no bloom season, so the timing remains unclear.

The species account says full shade and part shade both suit it. It needs moist soil that drains well. It can grow in sand, loam, or clay. The stated pH range goes from mildly acid to mildly alkaline. A separate note on garden sites favors shade with patches of light. It also favors shaded edges but rules out deep shade. This differs from the main guide to growing the plant. The notes agree most clearly on part shade. The source says its wider care notes draw on the genus, not just this species. It does not confirm how well this species withstands cold in Britain.

Plants For A Future says the plant is slow to increase. Its notes explain how to grow more from seed or by division. Division means splitting a plant into parts. The notes suggest sowing fresh seed in summer in a cold frame. They call for three weeks of cold treatment for stored seed. Sowing then takes place in late winter. Seeds sprout in spring, at times taking over four weeks. The notes advise shelter for young plants through their first winter. They also suggest splitting plants in spring or autumn. Keep the new parts in light shade until growth starts again.

Evidence for food use is weak and calls for care. One report calls the plant edible but names no part. Plants For A Future suggests the root but does not confirm this. The source reports no known cases of poisoning from this species. This lack of reports does not mean it is safe to eat. It lists no known uses as medicine or for other purposes. It also flags no risk of becoming a weed. The evidence names no pests or diseases specific to this species.