Trifoliate orange
| Trifoliate orange | ||||||||||||
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Trifoliate orange ( Poncirus trifoliata ), leaf and fruits |
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| Scientific name of the species | ||||||||||||
| Poncirus trifoliata | ||||||||||||
| ( L. ) Raf. |
The trifoliate orange ( Poncirus trifoliata ), even bitter orange or bitter lemon called, is the only sure-known species of the genus Poncirus in the family of Rutaceae (Rutaceae).
origin
Poncirus trifoliata comes from central and north China as well as Japan , is found there as a wild form and is often used as a hedge plant.
description
The three-leaved orange forms strongly thorny and matted growing shrubs or broad small trees that reach heights and plant diameters of up to 4 m. The bark stays green. The branches are clearly flattened. It is deciduous in winter and can withstand temperatures down to about −25 ° C. The leaves are in three parts, with the middle leaflet about 1/3 larger. The petiole is slightly winged. In autumn the leaves turn orange.
Flower buds for the following year are already clearly visible in autumn. The relatively large, hermaphrodite flowers stand alone, sometimes in pairs, in the leaf axils. The lightly nailed petals are about 2 cm tall. In contrast to the genus Citrus, the 20 to 23 stamens are free and not grown together. This self-fertile species is pollinated 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 a five to eight millimeter thick, hairy skin and often a small teat. It contains 25 to 40 seeds. The large seeds are smooth-skinned and polyembryonic . Their juice is acidic, mixed with unpleasant-tasting resin oil and inedible. Ripe fruits give off a strong citrus odor.
The number of chromosomes is 2n = 18, rarely 36.
use
The three-leaved orange is the hardiest citrus plant that is planted in Europe. She is the best rootstock for potted plants Culture and schwachwüchsige Engpflanzungen. There is a dwarf form, a maximum of 2 meters high with a corkscrew-like growth, called 'Flying Dragon' or Poncirus trifoliata var. Monstrosa . The thorns of this variety are curved backwards, the fruits slightly smaller than those of the species.
The three-leaved orange is one of the most important grafting documents in many parts of the world. Some of their hybrids are sometimes used even more intensively as grafting documents in commercial cultivation.
Crossed with the sweet orange , the hybrids are called citrange , with grapefruit and pomelo : citrumelo, with lemon : citremon, with bitter orange : Citradia, with tangerine : citrandarin. The collective term for these hybrids is × Citroncirus.
All of these F1 hybrids (F1 = 1st branch generation of two different species / genera) have one thing in common: They are no longer as frost hardy as Poncirus , but mostly still between −10 and −15 ° C. The fruits are invariably sour and also bitter to varying degrees. The vigor is usually significantly higher than that of Poncirus, and with a few exceptions the plants are at most partially leaf-shedding. Many breeds were created by Walter Tennyson Swingle ( US Department of Agriculture ) in the field laboratory in Eustis (Florida) at the beginning of this century . In the endeavor to get frost-hardier hybrids with better, edible fruits, backcrosses to orange, mandarin, kumquat and grapefruit with these F1 hybrids were often created later.
Sources and web links
- Gordon Cheers (Ed.): Botanica . Random House Australia 2003. German edition: Tandem Verlag GmbH 2003, ISBN 3-8331-1600-5 .
- Flora of Pakistan - Poncirus (English).
- Entry in Plants for a Future (English).
- Profile from the University of Ulm (English).
Individual evidence
- ^ Poncirus trifoliata at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis