Yellowhorn

Xanthoceras sorbifolium is a deciduous large shrub or small tree up to about 8 metres tall, with leaves divided into many narrow leaflets like those of rowan. In spring it carries large clusters of white flowers with a yellow centre that turns red as the flower ages. The fruit is a thick, green, pear-shaped capsule that splits into three parts to reveal rows of round, glossy, dark brown seeds around 1 centimetre across. The kernel inside is sweet and rich. The plant tolerates drought, cold and poor, alkaline or sandy soil.

Yellowhorn is native to northern China, including Inner Mongolia, Shanxi, Shaanxi, Hebei, Liaoning and Gansu, and parts of Korea, growing on dry hillsides and sandy slopes. It has been planted in many parts of northern China for erosion control and desertification control. It is now grown as an ornamental in parts of Europe and North America, but it is an edible nut and oil crop mainly in China, where plantations have expanded rapidly since the early 2000s.

The Chinese name, wenguanguo, means literary crown fruit, and the plant has long been cultivated near temples and gardens in northern China. The seeds were eaten as a nut for centuries, and the Compendium of Materia Medica and other traditional texts mention the plant. The genus name Xanthoceras comes from Greek words for yellow and horn, referring to the horn-shaped glands on the flowers.

In the twenty-first century, the Chinese government and companies promoted yellowhorn as an energy and oil crop for arid land, because it grows on marginal soils and produces seeds containing a high proportion of oil. Research has examined the oil composition, which is rich in unsaturated fatty acids including oleic and linoleic acid and also includes a small amount of nervonic acid. Food products and cosmetics made from the oil are marketed in China, and in the West the tree is mostly grown by plant collectors.

The kernels are roasted and eaten like nuts, or boiled and used in confectionery and baking. They are ground into flour, used in cakes and cooking, and pressed to make edible oil, sold in China as a health-promoting oil. The flowers and young leaves have been used as a vegetable or tea in some places, and the wood and shell by-products are used for fuel and as a source of natural chemicals. It is also a handsome garden shrub.

The kernels contain fat, mainly unsaturated fatty acids, along with protein and some carbohydrate. Oil from yellowhorn has attracted research interest for its fatty acid profile, including nervonic acid, a long-chain fatty acid found in nerve tissue. While early laboratory and animal studies are interesting, there is not enough human evidence to support health claims. Nutrient figures vary with source and are approximate. Seeds must be properly cooked or processed.