Adenium obesum
Family: Apocynaceae
​Common Name: ​desert rose
​Origin: Adenium obesum is widespread across East and Northeast Africa, and has naturalized in Sri Lanka and Thailand. The succulent prefers habitats with frequent summer precipitation and dry winters.
Description: A. obesum is a succulent shrub to small tree that possesses thick stems, a swollen caudex, and an open crown of glaucous leaves arranged in spirals at branch tips. Branches are crooked, glaucous to brown, and leafless along the body, often being evergreen in cultivation. During the summer, satisfied succulents will develop terminal clusters of showy flowers – pink to red, and occasionally white or with white centers – blooming for 2-3 days before perishing. Flowers will be followed by pale gray to brown fruits in the form of twin follicles that are united at the base, resembling the horns of an ox.
  • Interesting Features:
    • The desert rose has been hybridized extensively in population, with varieties that include orange and striped flowers. Additionally, the species can be turned into a striking bonsai within as little as 5 years.
    • For an unusual appearance, Adenium obesum can also be grown upside down. Remove the plant from its container, wash the root ball, and repot with the head in the soil and the roots emerging. Over time, sprouts, leaves, and even blossoms will develop from the sides of the root mass.
  • Uses: When wounded, A. obesum produces a milky sap that has been utilized extensively in Africa as a piscicide and poison, often used to douse arrows by the Swahili people.
    • Additionally, the desert rose possesses anticancer, antiviral, antibacterial, and other medicinal abilities, and may possibly be used as a source for future healthcare products.

Cultivation and Care:
  • Watering: Moderate
    • Water Adenium obesum in the early mornings of the growing season, and reduce irrigation in the winter. While the plant should not be kept waterlogged, it also must receive adequate moisture to encourage flowering.
  • Soil: Plant the desert rose in succulent soil, or regular potting mix supplemented with pumice, perlite, or sand.
    • Additionally, a pH between 6.0 and 7.0 should be maintained, being as close as possible to 6.0 for the best growth.
  • Lighting: While A. obesum appreciates sun, the species is very susceptible to scalding, and should be protected. Light shade or filtered sun is recommended, as too much shade will create leggy growth and reduce flowering.
  • Propagation: The desert rose can be propagated through seed, grafting, or cuttings. Plants grown from seed will resemble the parents at a young age, but plants grown from cuttings may require time in order to develop the swollen caudex.
  • Cold Tolerance: 30°F, USDA hardiness zones 10a to 11.
  • Special Accommodations: A. obesum should be protected from frost, and spider mites, to which the species is especially susceptible.
    • To maintain shape, prune regularly, and do not plant in a very deep pot, as this will lead to abnormal caudex development.
    • Always wear gloves when handling, and keep out of the reach of pets or children, to avoid poisoning by the toxic sap.

Sources:
  1. Llifle Encyclopedia of Succulents
  2. Plant Desert
  3. Dr. Duke’s Phytochemical and Ethnobotanical Databases
  4. Researchgate
  5. Oregon State University
  6. Missouri Botanical Garden
  7. The Spruce
  8. Plant Care Today
  9. Dave’s Garden