Citrus fruits - all orange, or what?

June 10, 2020 Fruit knowledge

The citrus plants (Citrus) are a genus of plants in the rue family (Rutaceae). They originate from the tropical and subtropical southeast of Asia. The representatives of this genus provide the citrus fruits (mainly oranges, tangerines, lemons and grapefruits), which are widely grown in the warm areas of the world. These fruits are a special form of berry, characteristic of the genus Citrus.

They are evergreen trees or large shrubs. They reach growing heights of about 5 to 25 meters. The flowers are white, the roundish fruits turn green, yellow or orange when ripe.

Branches, trunk and roots

The young twigs are green and angular. They have a ridge below each leaf base that slowly tapers downward. This results in a triangular cross-section, but this becomes less pronounced as they begin to grow thicker. Buds sit in the leaf axil, as well as sometimes one spine each. Thorns are often formed only on young plants or strongly growing branches. Sprouting buds may develop into purely vegetative shoots, shoots with leaves and flowers, or those with flowers only. Branches do not end their longitudinal growth with a terminal bud; the last lateral bud takes over this function (sympodium).

Older branches are round, their bark is thin, gray and smooth, the wood yellowish. The trunk is often crooked and splits into many irregularly branched branches just above the ground. Under favorable conditions, no pause in growth occurs; annual rings are formed only in climates with unfavorable seasons. Thickness growth may occur in several spurts during a growing season, so that xylem and phloem form structures resembling annual rings several times a year.

The root system consists of a taproot as well as lateral secondary roots. Two types of roots can be distinguished: thicker holdfast roots, which also show secondary growth in thickness, and thinner fibrous roots, which form branched tufts but hardly thicken. Fungi of the genus Glomus have been discovered as mycorrhizae.

(Source: Wikipedia)

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