The orange tree, typically the sweet orange (Citrus sinensis) or the bitter orange (Citrus aurantium), is a member of the citrus family (Rutaceae). This small to medium-sized evergreen tree is cultivated globally in tropical and subtropical climates for its fragrant blossoms and edible fruit. The species is thought to be a hybrid of the pomelo and mandarin. The tree is distinctive because it carries a dense canopy of foliage year-round, making it a permanent fixture in the landscape.
General Structure and Evergreen Foliage
Orange trees typically grow to be small to medium, with most cultivated varieties reaching between 15 and 30 feet in height. The tree develops a rounded, spreading, and highly branched canopy, often with a similar spread to its height, creating a dense crown of foliage. The trunk is generally short, supporting the weight of the dense branches. These branches may feature slender, sharp thorns, particularly on younger growth or in certain varieties like the sour orange.
The foliage provides a constant deep green color to the landscape year-round. The leaves are oval or ovate, ranging from four to fifteen centimeters long, and possess a glossy, dark green texture. When crushed, the leaves release a characteristic, aromatic scent, which is an identifying trait of citrus trees.
The Distinctive Orange Blossom
The orange blossom usually appears in spring. These flowers are small, waxy, and pure white, often appearing in clusters of up to six blooms near the leaf axils. Each blossom typically has five petals that open to reveal a yellow heart.
A defining characteristic of the orange blossom is its powerful and sweet fragrance, which can perfume the surrounding air over a distance. This intense aroma has made the blossom, especially from the bitter orange (Citrus aurantium), a prized ingredient in perfumery, where its extracts are known as neroli or orange blossom absolute. The abundance of these flowers attracts pollinators, setting the stage for fruit production.
Fruit Development and Appearance
Following the bloom, the fruit begins its development as a small, hard, green sphere. As the fruit grows, it assumes a globe-like to slightly oval shape, and the exterior develops a dimpled, grainy, and leathery rind. The rind contains oil glands responsible for the fruit’s aromatic essential oils and carotenoids, which give it its final color.
The transition to the familiar bright orange or yellow-orange color occurs as the fruit ripens, often triggered by cooler temperatures. However, in truly tropical climates, the fruit may remain entirely or partially green even when ripe, as the color change is not necessary for internal maturity. The mature fruit hangs heavily from the branches, and a unique visual trait of the orange tree is its ability to simultaneously bear ripe fruit, developing green fruit, and new blossoms across different seasons.