Codiaeum is a genus of flowering shrubs in the family Euphorbiaceae (order Malpighiales), first formally described as a genus by Adrien-Henri de Jussieu in 1824, based on earlier work by Rumphius. The genus is native to insular Southeast Asia, Papuasia, and northern Australia, where its species grow in tropical forest margins and coastal scrub.
Members of the genus are evergreen, monoecious shrubs with thick, leathery, alternately arranged leaves. They bear long raceme inflorescences with male and female flowers separated on the same plant: male flowers are white with small petals and numerous stamens, while female flowers are yellowish and apetalous. The fruit is a small capsule, and the plants produce a milky caustic latex when cut — characteristic of the broader Euphorbiaceae family. The entire plant is toxic to most mammals, containing the alkaloid 5-desoxyingenol and a violently purgative oil.
Codiaeum is closely related to the genus Croton and is frequently confused with it; historically, several species now placed elsewhere (in Austrobuxus, Baloghia, Blachia, Fontainea, Sphyranthera, and Trigonostemon) were included in Codiaeum.
The genus is best known through its type species, Codiaeum variegatum — widely grown as an ornamental houseplant and tropical garden shrub under the common name "croton." This species displays an extraordinary range of leaf forms and colours across its more than 300 cultivars, with foliage variegated in combinations of green, yellow, orange, red, purple, and pink. In tropical climates it is used as a hedge or patio specimen; in temperate regions it is grown indoors or in greenhouses, requiring temperatures above 10–13 °C.
Etymology
The genus name Codiaeum is latinised from Kodiaeho, a local vernacular name recorded by the Dutch naturalist Georg Eberhard Rumphius in the Moluccas (Maluku), and was formalised by de Jussieu in his 1824 Euphorb. Gen. The common name "croton" is shared with the related genus Croton, reflecting the historical confusion between the two groups.
Distribution
Codiaeum is native to insular Southeast Asia (including Borneo, Java, the Philippines, Sulawesi, and the Lesser Sunda Islands), Papuasia (New Guinea, the Bismarck Archipelago, and the Solomon Islands), northern Queensland in Australia, and scattered Pacific islands including Fiji and Vanuatu. The most widespread species, C. variegatum, has been introduced to tropical regions worldwide through cultivation.
Cultivation
Codiaeum variegatum and its cultivars are widely grown as ornamental plants for their striking, vividly coloured foliage. In tropical and subtropical climates they thrive as outdoor hedges or container plants; temperatures below 10–13 °C cause leaf drop and the plants cannot survive frost. In temperate regions they are cultivated as houseplants or in heated greenhouses. Over 300 cultivars exist, selected for variation in leaf shape (from linear to ovate, entire to lobed) and colour (green, yellow, orange, red, purple, pink). Contact with the milky latex should be avoided, as it is caustic and can cause contact dermatitis; the plant is toxic if ingested.
Taxonomy
Codiaeum was first described as a genus by A.Juss. in Euphorb. Gen.: 33 (1824). Its synonyms include Phyllaurea Lour., Junghuhnia Miq., Crozophyla Raf., and Synaspisma Endl. The type species C. variegatum was originally described by Linnaeus in 1753 as Croton variegatus. Several taxa formerly placed in Codiaeum have since been moved to Austrobuxus, Baloghia, Blachia, Fontainea, Sphyranthera, and Trigonostemon. The genus is placed in Euphorbiaceae, order Malpighiales.
