Adeniums, while native to Africa and the Arabian Peninsula (1), are gaining popularity worldwide. Known by a variety of names, though some misleading, a common name which could be deemed appropriate, possibly because of its derivation, is the desert rose. While some still hold on to the Adenium as a single genus species (2) with variations, it is becoming better recognised as a genus with several distinct species and varieties. (3) Adeniums are a hardy succulent with a captivating and spectacular display of flowers, commonly in shades of white, red and pink. The ornamental gardeners are able to take advantage of this beautiful display and promote, create selections and develop new hybrids, suitable for garden and container planting. With stunning and unusual thick caudices (4), it is also popular amongst bonsai enthusiasts. While the medicinal and toxic properties of the Adenium plant has long been recognised in the native lands, currently peer reviewed literature and research can be found worldwide as the Adenium plant is being studied for medicinal and scientific advancement.
Adeniums come from the Apocynaceae family and range in size from shrubs with exposed or above ground caudices to small trees with swollen trunks with stems reaching up to 15 feet tall. In nature, they can be found in sandy soil in full sun. Their thick caudices and roots swell for water storage for the dry arid environments of both Africa and Arabia and cold weather induces dormancy over the winter period. It is known to attract bees, moths and some butterfly, mainly in its native or environments with similar attributes.
As the Adenium has been introduced to other countries, some confusion has arisen to the name and the genus. As it was introduced in to the Asian countries for example, it became known as the Japanese frangiapani, which is misleading as it is not a frangiapani. The common name Adenium is known by, is desert rose. Some authors recognize Adenium obesum as the only species in the genus. (5) Others, including organisations, recognize multiple distinct species in the genus. (6) Some are Adenium obesum, multiflorum, swazicum, boehmianum, oleifolium, somalense, crispum, arabicum, socotranum, tanzania and oman. All of these species, from time to time, can be referred to as the desert rose, but it is the Adenium obesum that is most represented by this name and is the most common amongst growers.
All species have a striking display of flowers. While shades of pink, white and red are common, there are also bicolours and other shades such as mauve in the public domain. Seeds are the more desirable way of producing Adenium to retain the thick caudex. If grafting or propagating, the stems can become a bit weak. As the seed does not always stay true to the mother plant, and the propagation of cuttings results in a weak stem, plant tissue culture is a way to achieve the best of both of these worlds. It is desirable to plant Adenium in a garden or a container with well-drained soil and full sun. They will not tolerate damp cold climates and are prone to frost.
The Adenium plant is important in traditional medicine. The sap in the plant contains a toxic poison. It has been used as an arrow poison in Africa to hunt large game. (7) A decoction from the roots has been used to treat venereal disease; baths and lotions have been created from bark and root extract to treat skin diseases and head lice; latex, produced from wounding the plant, has been used to treat septic wounds and also kill lice, while powdered stems are used on cattle and camels to kill skin parasites (8)
From these traditional medicines and recognition of plant properties comes the development of studies where the Adenium plant can be of great benefit. From the study of methanol extract of the Adenium obesum interrupting the reproductive system and thus containing snails (9) to using the Adenium obesum plant in the treatment of various infectious diseases caused by bacteria (10), to the inclusion of Adenium leaves as an anti cancer agent (11). The translation of traditional medicine and values to modern medicine and technology is promising.
But for all of the traditional, modern, medical or practical uses the Adenium plant can be appreciated for, many will simply be captivated by its beauty.