1227 Poncirus trifoliataCommon Names: trifoliate orange, hardy orange Family: Rutaceae (citrus Family)
Most citrus trees are evergreen, but trifoliate orange is deciduous. This tree is viciously thorny with large, sharp spines on all the stems and branches. Trifoliate orange is a rounded shrub or small tree that can get up to 15 ft (4.5 m) in height with a similar spread. Young shoots are green, stiff, and triangular in cross section. The shiny dark green leaves are 3-palmate and arranged alternately on the stems. They often turn yellow before dropping in autumn. The white flowers are typical looking citrus blossoms, cup shaped with five petals, up to 2 in (5 cm) across, and sweetly fragrant. They appear before the leaves in spring. The fruits are orange when ripe in late summer, about 2 in (5 cm) in diameter, and very sour.
The cultivar ‘Flying Dragon’ has weirdly contorted stems and branches.
Poncirus trifoliata is native to central and northern China and Korea where it grows in mixed woodlands. Trifoliate orange is widely used as a rootstock for various cultivars of Citrus, especially in Florida. It has escaped cultivation in many areas and persists in disturbed woods and abandoned fields in the southeastern U.S.
Light: Trifoliate orange does best in full sun but still does quite well in half shade. Moisture: This little citrus tree likes a fertile, well drained, acidic soil. Once established, trifoliate orange can survive moderate dry periods. Hardiness: USDA Zones 6 - 9. Because trifoliate orange goes dormant in the winter it can survive in much colder regions than the true Citrus species which do not lose their leaves in winter and continue growing. In protected sites it can survive in zone 5. Propagation: Seed is the main method of propagation and may be sown in autumn. Cuttings may be started any time. Trifoliate orange sometimes spreads by seeds all by itself and may be found growing wild in mixed woodlands near where it had been used as a rootstock.
Trifoliate orange is a beautiful little tree with wonderfully fragrant blossoms in spring and pretty orange fruits in summer. The fruits are very seedy but the juice can be used wherever a sour citrus juice is needed. The peels can be candied and a marmalade can be made from the pulp. In winter this spiny tree, devoid of leaves and fruits, makes a beautiful silhouette in the landscape.
Grow trifoliate orange in a shrub border or in a hedge where its treacherous spines cannot do harm to life or limb. It sometimes is planted as a barrier hedge through which neither man nor beast would voluntarily pass. Trifoliate orange in a hedge can be pruned severely to create a boxwood-type wall.
Trifoliate orange is the preferred rootstock for most Citrus species grown in northern Florida, especially satsuma and grapefruit. This is because trifoliate orange goes dormant in winter, thus reducing the activity and growth of the cultivar that is grafted on it. Citrus trees grown on trifoliate orange rootstock are always the most cold tolerant citrus. However, they must develop cold tolerance each winter. Trees grown on trifoliate orange rootstock develop their best cold tolerance when they are exposed to at least two weeks of nighttime temperatures below 50° F (10° C) before freezing temperatures. A subsequent warm spell can reverse the cold tolerance and stimulate tender new growth.
Trifoliate orange is the only species in its genus.
Be careful of those cruel thorns!
Steve Christman 10/31/14