Trifoliate orange

Poncirus trifoliata, leaf and fruit.

The Three-leaved orange ( Poncirus trifoliata ), also known as bitter orange or bitter lemon, is the only known species of the genus Poncirus safe in the rue family ( Rutaceae ).

Origin

Poncirus trifoliata is native to central and northern China and Japan, is to be found there as a wild form and is often used as a hedge plant.

Description

Poncirus trifoliata is heavily spined and matted growing shrubs or small trees wide, reach the heights of growth and plant diameter of up to 4 m. The bark remains green. The branches are significantly flattened. It is winter deciduous and can withstand temperatures to about -25 ° C. The leaves are in three parts, wherein the average flake is greater by about 1/3. The petiole is slightly winged. In autumn, the leaves turn orange.

Flower buds for the following year are already clearly visible in the fall. The relatively large, hermaphroditic flowers stand alone, sometimes in pairs in the leaf axils. The slightly spiked petals are about 2 inches tall. The 20 to 23 stamens are in contrast to the genus Citrus free and not fused. The pollination of these self-fertile species carried by insects. The flowering period extends from April to May

The round fruit has a diameter of 3 to 5 centimeters is yellow to yellow- orange, with five to eight millimeters thick, hairy shell and often a small teat. It contains 25 to 40 seeds. The large seeds are smooth skin and polyembryonisch. Its juice is sour, unpleasant -tasting resin mixed with oil and inedible. Ripe fruits give off a strong citrus smell.

Use

The Three-leaved orange is the best rootstock for pot plant culture and schwachwüchsige Engpflanzungen. There is a dwarf, a maximum of 2 meters tall form with corkscrew- like stature, 'Flying Dragon' Poncirus trifoliata var or monstrosa called. The spines of this species are bent backwards, the fruit slightly smaller than the species

The Three-leaved orange is one of the most important rootstocks in many parts of the world. Some of their hybrids are more intense partly used as rootstocks in commercial cultivation.

Crossed with Sweet Orange hybrids are called Citrange, with grapefruit and pomelo: Citrumelo, with lemon: Citremon, with Bitter Orange: Citradia, with mandarin: Citrandarin. The collective term for these hybrids is × Citroncirus.

All these F1 hybrids (F1 = first filial generation of two different species / genera ) one thing in common: They are not quite as hardy as Poncirus, but still mostly -10 to -15 ° C. The fruits are all acidic and in varying degrees also bitter. The vigor is usually significantly higher than in Poncirus, and with few exceptions, the plants are most partially deciduous. Many varieties are early in this century by Walter Tennyson Swingle (U.S. Department of Agriculture) in the field laboratory in Eustis (Florida ) emerged. In the effort to get frost harder hybrids with better, edible fruits, backcrosses to orange, mandarin, kumquat and grapefruit with these F1 hybrids are often later developed.

Sources and links

• Cheers Gordon (ed.): Botanica. . Random House Australia 2003 German edition: Tandem Verlag GmbH 2003, ISBN 3-8331-1600-5.
• Flora of Pakistan - Poncirus. (English )
• Entry at Plants for a Future. (English )
• Profile of the University of Ulm. (English )

• Rutaceae
• Citrus fruit