Japanese Raisin Tree

Common names

• Japanese Raisin Tree
• Oriental Raisin Tree
• Raisin Tree

The Japanese raisin tree can be found all over the Asian continent, from heights of over 2000 m in the Himalayas to the Eastern parts of China and Korea. It enjoys soils made up of sand or loam and locations with full sun exposure. The tree is cultivated in many other countries of the world as an ornamental plant because of its beauty and the useful edible fruit. In Brazil, it has become a very aggressive invasive species in the subtropical woods. The tree is part of the buckthorn family, in the genus Hovenia and the family Rhamnaceae. This genus only includes three species actually, the others two are trichocarpa and acerba. The Japanese raisin tree has the name dulcis and is further divided in two varieties names koreana and tomentella. Acerba and dulcis plants are known for their medical benefits. When cultivated, this deciduous tree normally has a round crown and a single trunk that reaches a height of about 30 feet. However, it can grow as high as 70 feet in the wild. Since the lower branches usually fall off, the trunk tends to branch quite high. It grows faster in its youth and slower as it gets older, but the rate never exceeds one or maybe two feet per year. The bark is irregular and covered with deep cracks but the branches and the leaves make the Japanese raisin tree popular for ornamental purposes. Planting the trees in groups increases their visual appeal. Leaves are green and glossy, growing in alternate fashion. Every leaf is cordate and large in size, their real shape can only be revealed by spreading them wide. The flowers are able to pollinate themselves and can be found on racemes. The small flowers have a cream-like color and bloom at the end of spring. They are grouped in large clusters, even if the individual flowers are small. Sometimes the flowers only emerge at the end of summer if the weather is cold, which can hurt the fruit production. The fruits are known as raisins and are edible. In reality, they are not actually fruits but oversized flower stalks. The seed pods at the end are the actual fruits of the plant, which are not edible. The stem peduncle that supports the seed pod becomes red or brown as the fruit matures and can be consumed when it falls naturally to the ground. They have a high sugar content and a taste similar to a pear. While the peduncles are not bigger than a raisin, the tree produces them in large numbers. The brown seed pods fruits are discarded.

Uses

In Chinese traditional medicine, Japanese raisin tree is considered a powerful remedy against hangover that is widely available in nature in both China and the neighbouring areas. The edible peduncles or the fruits are normally the parts used in medicine. The peduncles are the stems that support the flowers and are said to taste between cinnamon, cloves and normal raisins. Modern research has validated the claims of ancient Chinese medicine. Even if lab tests have not been fully completed, the plant was found to reduce inflammation and have anti-viral properties. It also prevents the production of histamine and various other compounds that cause allergies in the body, while acting like a bronchodilator. Japanese raisin tree is effective against asthma, eczema, fibromyalgia and other similar problems. The Japanese raisin tree might also be a cure for fever, since it is known to reduce inflammation. It also treats gastric issues, reducing spasms. In general, it can relieve numerous types of digestive and stomach problems, regardless of their cause. It has a detoxifying effect by boosting the rate of toxin elimination from the body, while it reduces swelling and relieves abdominal and intestinal pain. The Japanese raisin tree is valued in the traditional medicine of several Asian countries, like China, Korea and Japan. It is used against hangover and as a cure for liver diseases, fever and parasitic infestation. The Japanese raisin tree also has a number of industrial uses, the hard wood being a quality furniture material as well as a construction structural item.

Habitat and cultivation

The Japanese raisin tree needs sun exposure and likes fertile soils with a content of sand or loam. The small flowers are located on terminal cymes and have a pleasant smell. It is grown for its fruits in Japan and other areas of Asia. As a deciduous tree, the Japanese raisin tree tolerates cold temperatures well. The young shoots are still vulnerable to late onsets of frost. The Japanese raisin tree can also survive drought to an extent but needs constant water for best results. However, the plant will die if submerged. Propagation of the Japanese raisin tree can be done using the seeds, which germinate fast if placed in a cold frame when they become ripe. The seeds can also be stored for later use, but in this case germination is a lot slower and can even take one year. As soon as the seedlings are big enough, they can be relocated individually to pots and placed in a greenhouse for the first winter. As soon as the frosts are gone at the end of spring, the plants can be moved outside but some protection is required during the winter. They can also be propagated by cuttings of both crude and mature woods, in a frame in late summer or autumn.