Choisya is a small genus of aromatic evergreen shrubs in the rue family (Rutaceae, order Sapindales). Members of the genus are commonly known as Mexican orange — a reference to the shape and scent of their flowers, which resemble those of the closely related orange. Native to southern North America, from Arizona, New Mexico, and Texas south through most of Mexico, these shrubs typically reach 1–3 metres in height. The leaves are opposite, leathery, glossy, and palmately compound, with 3 to 13 leaflets depending on the species — C. ternata has three broad leaflets, while C. dumosa bears up to 13 very narrow ones. The star-shaped flowers are 3–5 cm across, with 4–7 white petals, 8–15 stamens, and a green stigma; they appear profusely from late spring through summer. Each flower yields abundant nectar, making the genus a valuable honeybee forage plant. The fruit is a leathery capsule divided into two to six sections. The foliage is aromatic, releasing a rue-like scent when bruised or cut. The genus was named by Humboldt and Bonpland in honour of the Swiss botanist Jacques Denis Choisy (1799–1859). Choisya species are widely cultivated as ornamentals in regions with mild winters, prized for their fragrant, long-lasting blooms; several cultivars of C. ternata and the hybrid C. × dewitteana have earned the Royal Horticultural Society's Award of Garden Merit.
Etymology
The generic name Choisya was given by Alexander von Humboldt and Aimé Bonpland in honour of the Swiss botanist Jacques Denis Choisy (1799–1859), a specialist in the Convolvulaceae family.
Distribution
Choisya is native to southern North America, ranging from the southwestern United States (Arizona, New Mexico, Texas) southward through most of Mexico. The genus is widely cultivated as an ornamental in temperate regions worldwide with mild winters.
Ecology
The flowers produce abundant nectar and are valued as a forage source for honeybees. The foliage is aromatic — when bruised or cut it releases a scent reminiscent of rue (Ruta), which is consistent with the genus's placement in the Rutaceae family.
Cultivation
Choisya species are popular ornamental shrubs for mild-winter gardens, grown primarily for their abundant, fragrant white flowers that appear from late spring through summer, and their glossy evergreen foliage. Several cultivars have received the Royal Horticultural Society's Award of Garden Merit, including Choisya × dewitteana 'Aztec Pearl', Choisya × dewitteana White Dazzler ('Londaz'), Choisya ternata, and Choisya ternata Sundance ('Lich'), the latter bred by Peter Catt in 1986.
