Japanese White Birch
Japanese White Birch
Betula platyphylla
“The white tree of the north”
| Species | Betula platyphylla |
|---|---|
| Family | Betulaceae |
| Part used | Leafy twigs and bark |
| Aroma | Soft and green, as the leaves revive in hot water |
What is shirakanba?
The Japanese white birch (Betula platyphylla) is a deciduous tree found from central Honshu northward into Hokkaido, at higher elevations and in the subalpine zone, and it is especially common in Hokkaido. Outside Japan it grows in China, the Korean peninsula, Mongolia, the Russian Far East and Siberia. It is the tree of Nagano Prefecture.
The bundle called vihta
The vihta (also vasta) used in the Finnish sauna is a bundle of birch twigs with their leaves. The same object is viht in Estonian, vanta in Lithuanian, and venik in Russian. The species matters here: according to the Finnish Sauna Society and Finnish-language sources, a vihta is made from silver birch (Betula pendula) and downy birch (B. pubescens) — not the Japanese white birch (B. platyphylla), which stands in for them in Japan. In Finland the bundles are cut between midsummer and early July and are best used within two days. Finnish sauna culture itself was inscribed on the UNESCO list of intangible cultural heritage in 2020 (the inscription makes no mention of the vihta).
Used as the vihta, a bundle of leafy twigs. Dried bundles are revived in hot water to raise their scent, hung in the sauna room, or brushed against the body (whisking). Finnish sources say the saponins in birch leaves were held to act as a mild soap and to stir up circulation at the surface of the skin, and the whisk is also said to have soothed the itch of mosquito bites. Japanese saunas list it variously as shirakaba, shirakanba or vihta.
The National Ainu Museum records that the Ainu drank the sap that ran from a cut in the trunk in early spring, and that on Sakhalin it was fermented into a drink; the bark was worked into all manner of vessels and containers. In some regions the sap is still tapped in early spring. The white bark peels away in thin sheets and has been worked in Ainu craft and in Nordic birch-bark work. (Akita's kaba-zaiku, despite the name, uses wild cherry bark and is a different craft.)
Note: this page introduces the traditions and culture around the plant. It does not guarantee any effect.