– Adenium obesum (2009)

By Joe Merkelbach (June 2009)

Since our show T-shirt will feature Adenium obesum for 2009, I thought it would be worthwhile to put out the information I have discovered while researching so everyone will have some talking points while working at the event.

The genus Adenium is another playground for taxonomists. In the past, as many as 12 species have been recognized, but recently these were combined into only one by one authority, though some name five or six species. A. obesum is certainly the most widely known name, with many hybrids involving the various subspecies producing white to red flowers in copious quantities.

Adeniums, whether they have full or subspecies status, are all natives of the warm regions of eastern Africa and the Arabian peninsula, areas where the habit of succulence to store water over dry times is a very valuable trait. Some pictures of the plants in habitat show impressive water storage caudicies.

The plants need warm conditions with temperatures above freezing all year to thrive, but can handle full sun readily and take lots of water while they are actively growing. They can drop leaves if exposed to cold or extreme aridity, but will recover if treated properly.

Adeniums are members of the Apocynacae, a family found in both the Old and New World tropics. The common name for the family is dogbane, and the juice of many members, including A. obesum, is milky and toxic. The milkweed group, Asclepidaceae, is allied to Apocynacae and has now been included within the family. Any stem cutting or grafting for propagation should be done with care – treat the juice as you would euphorbia latex.

The basic adenium flowers are tube-shaped with five petals that open rather stiffly at right angles to the tube. Blossoms have a white “target” center surrounded by pink edges to attract pollinators. These attractive flowers and ease of care have been a ticket for adeniums to spread around the world as house plants. They are favorites for outside growth in warm climates, as well.

After carrying example plants from working sites in the oil-rich areas of the Mideast back home, southeast Asian hybridizers have been very active in using the methods of crossbreeding and grafting to produce many flower varieties, including doubles and shades tending toward yellow and purple.

The succulence and xeric growth habits have not been so greatly modified and have mostly been along for the ride in this work. However, variegated and dwarfed plants have been developed.

Some spectacular images of these plants can be found on the World Wide Web. See:

Xxxxxx – http://en.wikipedia.org/wiki/Adenium
Xxxxxx – http://images.google.com/images? hl=en&q=adenium+obesum&um=1&ie=UTF-8&ei=BAQiSriTKIvoNM6akLQJ&sa=X&oi=image_result_group&resnum=4&ct=title
Xxxxxx – http://www.flickr.com/photos/pkerror/