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Adenium obesum (Forssk.) Roem. & Schilt. 1819
pronounced: uh-DEE-nee-um oh-BEE-sum
(Apocynaceae – the oleander family)
common name: Desert Rose
Adenium is named for Aden, the former name of Yemen, where the species is native. Pehr Forsskal (1732–1763), the first European to see the desert rose, was a child prodigy who became an undergraduate at the University of Uppsala when he was 10 years of age. He studied botany under Linnaeus, and was also a student of philosophy and theology. In an age where every man’s place in society was firmly established, he submitted a thesis on civil liberty, which did not go down well! Linnaeus confiscated the thesis, and it was condemned by all the churches. In 1761 with 5 others Forsskal joined an expedition, funded by the King of Denmark, to explore Egypt, Arabia and India. After 9 months in Egypt, the team landed in Yemen late in December, 1762, and Forsskal discovered the desert rose. He died a few months later: indeed, only one member of the expedition survived to complete the expedition’s mission.
Obesum in Latin means ‘fat, gross’. Adenium is a genus of spectacular succulents from tropical Africa and Arabia. The plants range from shrubs with subterranean or above-ground caudices to small trees with swollen trunks and stems growing 4 or 5m tall. Their striking forms are further enhanced by some of the showiest flowers of all succulents, often borne in masses over a long season.
Adenium obesum is an evergreen or semi-deciduous succulent shrub, that is similar in may ways to its relative the frangipani. It grows 1–3 m high, with thick, fleshy branches, and with age develops a swollen base, hence obesum. The glossy green leaves are spirally arranged, clustered towards the tips of the shoots. They are simple, entire, leathery in texture, anything up to 15 cm long and 8 cm broad.
The flowers are tubular, 2–5 cm long, with the outer portion 4–6 cm in diameter with 5 petals, resembling those of other related species as frangipani and oleander. The flowers of the various cultivars usually tend to red and pink, often with a whitish blush in the throat. It is a popular houseplant in temperate regions, but it requires a sunny location and a minimum temperature of 10ºC. Being a plant from arid regions, it thrives on a similar watering regime to cacti.
Desert Rose plants grown from seed develop the best character by far, with no two plants being alike in shape. Thin bean-like seed pods are produced in pairs. When the seed pod is fully ripe on the plant, it splits open, revealing dandelion-like fluffy seeds that quickly blow away. For best germination, seeds should be planted immediately the pods open. Plants grown from seed will not remain true-to-type, and will often produce offspring that bear flowers of a different colour from those of the parent plant. When branch cuttings are used for propagation, the plant is usually inferior in appearance, and the swollen base does not usually develop.
The plant exudes a highly toxic sap which is used by some tribes, notably the Akie in Tanzania, to coat arrow-tips for hunting, and for a fish poison.
Photographs taken in Picnic Bay , 2007-2018
Page last updated 18th August 2018