Sharinbai, the Yeddo Hawthorn: The Seaside Shrub Behind Japan's Black Oshima Silk
In autumn, a tough little evergreen in Japanese gardens and along coastal roads carries clusters of round, blue-black berries. They look like small blueberries, and people often ask if they can eat them.
They are not something people eat. The fruit is small, the skin is thick and there is very little inside. But the plant has a far more interesting use, and it is hidden in its bark.
The plant is sharinbai, known in English as Yeddo hawthorn. We are a small tree care and landscape business in Mie Prefecture, central Japan, and we see it in many of the gardens we look after. This page explains what it is and why it matters to one of Japan's most famous textiles.
A wheel of leaves and a plum-like flower
Sharinbai is Rhaphiolepis indica var. umbellata, also listed as Rhaphiolepis umbellata, an evergreen shrub in the rose family. In Japan it grows wild near the coast, often on sandy ground, from central Honshu west to Shikoku and Kyushu, and also in Taiwan, Korea and China. It usually stays about 1 to 2 metres tall.
The Japanese name means "wheel plum". The leaves gather at the tips of the shoots like the spokes of a wheel, and the white flowers, which open from April to June, look like plum blossoms. The fruit ripens in October.
It tolerates salt wind and city air. That is why it is so often planted along roads, in car parks and in seaside gardens in Japan.
Teechi-gi: the dye tree of Amami
Far to the south, on Amami Oshima, an island between Kyushu and Okinawa, the same plant has a local name, teechi-gi. Its bark and wood are the dye behind Oshima tsumugi, the island's famous hand-woven silk.
The black of traditional Oshima tsumugi is made with a method called dorozome, which means mud dyeing. The name is a little misleading, because the first step is not mud at all.
Chips of sharinbai wood are boiled in a large pot, and the silk thread is soaked in the brown liquid. The plant is rich in tannin, and the thread takes on a reddish brown.
Then the thread is taken to a mud field and worked in the mud. Iron in the mud reacts with the tannin from the sharinbai, and the colour turns darker. The two steps are repeated again and again, alternating between the sharinbai dye and the mud. One weaving house on the island says the bond is built up more than 85 times, until the thread becomes a deep, soft black that does not fade.
Why island plants dye darker
Sharinbai grows on the coasts of Honshu, Shikoku and Kyushu too. But the people who dye with it on Amami say the island's plants make a darker colour. The strong sun and sea wind there push the plant to make more tannin, which protects it.
The dyers use a lot of it, about 600 kilograms of wood chips at a time. Nothing is wasted. The boiled chips are dried and burned as fuel for the next batch, and in the past the ash went to local sweet makers for akumaki, a traditional rice cake.
To us this is a good example of a small, ordinary garden plant carrying a whole culture. The same shrub we trim beside a car park in Mie becomes, on Amami, a black silk worn for generations.
Sharinbai in the garden
Sharinbai is easy to grow and needs very little care. It keeps a dense, rounded shape, so it works well as a low hedge or a single shrub. In spring you get the white flowers, and in autumn the dark berries.
If you see a tidy evergreen shrub with blue-black berries by the sea in Japan, look closely at the leaves. If they gather like the spokes of a wheel, it is probably sharinbai.
