Stellenbosch University Botanical Garden, South Africa

Common name: Chinese bitter orange, hardy orange, Japanese bitter-orange

Family: Rutaceae (Rue)

Synonym: Poncirus trifoliata

Distribution: Northern China and Korea

Life form: Evergreen tree

Comments: Trifoliate orange and hybrids of this species are widely used as citrus rootstock. Productive citrus of various types are grafted onto roots of this plant which is valued valued for resistance to cold, virus, and the fungus Phytophthora parasitica (root rot). The plant contains a high concentration of auraptene which is one of the functional components providing immunity against citrus tristeza virus.
Trifoliate orange is seldom grown for its aerial parts as the fruits are very bitter, in part due to to high poncirin content. Most people consider them inedible fresh, but they can be made into marmalade or dried and powdered and used as a condiment. The fruits are widely used in traditional medicines of East Asia as a treatment for allergic inflammation.