Mulberry Wood

Yamaguwa grows from Hokkaido through Honshu, Shikoku and Kyushu to Okinawa, and on the Izu Islands as the variety hachijōguwa; the standing stock is very small, so its uses are limited. Flora of China records Morus australis in much of China and Taiwan and in Bhutan, India, Japan, Korea, Myanmar, Nepal and Sikkim. Many mulberries grown for silkworms in Japan are said to be yamaguwa lines, and the Chinese tōguwa (a variety of Morus alba) was introduced for sericulture in the early Meiji era. The famous 'island mulberry' (shimaguwa) of Mikurajima in the Izu Islands is botanically classed as hachijōguwa; it grows on steep, wind-exposed slopes with narrow, dense growth rings, and a 2017 Forestry and Forest Products Research Institute study found its harvest had declined markedly, with sales coming mainly from stock.

Yamaguwa is a ring-porous wood, so growth-ring boundaries are clearly visible and the texture is coarse; the heartwood is sharply distinct from the pale sapwood. Its grain is often irregular, producing figures such as jorin-moku, tama-moku and botan-moku. It is fairly hard to cut but finishes to a beautiful surface and is highly durable. Craftsmen describe Mikurajima mulberry as yellowish when freshly cut and turning, without any coating, to a clear brown over 40–50 years.

In Japan mulberry wood has been used mainly for Japanese furniture (especially mirror stands), sashimono joinery, carving, musical instruments and turned work. In Edo sashimono, mulberry from the Izu Islands of Miyakejima and Mikurajima is regarded as the finest material; it was nicknamed 'gold mulberry' (kinkuwa, ōgonkuwa), and in the Meiji era woodworkers who made masterpieces from island mulberry were called sōjushō. A Tokyo sashimono craftsman explains that Miyakejima mulberry was used first because it was easier to ship, was largely cut out from the Meiji era onward, and that Mikurajima mulberry survived because large boats long could not reach the island.