Description

General aspect and origins - Poncirus trifoliata, also known as trifoliate orange or Japanese bitter orange, is a close relative to the Citrus trees. It a decidious or semi-decidious tree which is native to China. Leaves are trifoliate, and flowers are white, simple and often fragrant. It bears inedible fruits that look like small Citrus fruits.
Leaves - Leaves of the Japanese bitter orange are decidious to semi-decidious. They are alternate and trifoliate, and are up to 2 in (5 cm) long. As many Citrus trees, the petiole is more or less winged.
Flowers - Flowers are white and simple. These flowers, which appear in spring, have 5 petals and are often fragrant.
Fruits - Trifoliate oranges are small fruits, yellow when ripe, looking like small oranges, whith a slighly pubescent skin. The flesh, which is inedible, contains many seeds.

Culture

This little tree is very frost hardy, as it will withstand frosts down to -5°F (-21°C) and lower. It can thus be grown in USDA zones 6 and warmer. This tree has sharp spines that can be up to 2 in long.
Soil - The trifoliate orange dislikes alcaline soils.

Propagation

Poncirus trifoliata is propagated by seeds. Seeds must be as fresh as possible. The trifoliate orange is often used as a rootstock for many Citrus species and varieties, as it is known to improve frost hardiness and fruit quality.