John&Jacq~s Garden

Posted by Jacqueline on October 7th, 2008 in Plants database

Adenium obesum (Desert Rose, Mock Azalea, Impala Lily)

Its beautiful clusters of colorful flowers are obviously an attraction! But it is the uniquely-shaped swollen bases of Adenium obesum that have always fascinated us, though we never had a strong urge to own one. However, sometime in December 2005 we decided to add a seedling about 13cm tall to our garden.

To our disappointment, it was so slow-growing, hardly increasing upwards, sidewards nor developed a swollen base as expected.

Such slow-growth can be quite depressing if one is impatient to see results. Even though new leaves emerged as the older ones are shed ever so frequently, a single non-blooming spindly stem that is sometimes almost devoid of leaves is so unappealing.

Then, in May 2007 one and a half years later, still single-trunked but grown almost double in height, it finally sprung a lovely surprise and started budding for the first time ever! And then, flowered again 6 months later on its completely defoliated trunk.

It looked so gorgeous the first time around that we could not resist but got ourselves another 2 seedlings of the dwarf variety a few months later. They are a year-old now, not flowered yet but the swollen bases are distinct and lovely. Hehe, at least we get to delight in the beauty of their caudex for the moment.

Recently, we saw a beautiful potted Adenium obesum shrub about a meter tall with overflowing dark-red blooms in someone’s garden. It was so captivating and inviting. Many a time, as we drove past that house, I was tempted to request a shot of it from its owner, but John, my beloved spouse did not support the idea. Aargh, otherwise I could have shared a picture here! We have never seen a shrub that tall and so beautiful before, wonderfully multi-branched and abundantly filled with foliage and flowers! An amazingly stunning shrub indeed! Make us want to get another, but definitely not a dwarf variety again!

Ignorance is no bliss! Hopefully, having researched further about its culture and others to share them here, we’ll be ‘better parents’ now that we are better equipped.

Plant Profile, Culture and Propagation :

• Botanical Name: Adenium obesum
• Common Name: Desert Rose, Mock Azalea, Impala Lily, Sabi Star, Kudu
• Family name: Apocynaceae
• Plant type: Succulent flowering shrub or small tree, native to Eastern Africa and Southern Arabia.
• Features: Adenium obesum is a succulent perennial shrub/small tree that can reach 1-3m tall, though most cultivated hybrids and varieties grow between 0.5-1.5m tall and bonsai, much shorter. It is a highly variable species, ranging from slow to vigorous growth rate, producing either a single thick fleshy trunk/stem or a multitude of succulent stems (that emerge naturally or aesthetically by tip-prune), grey or greyish green in color. Most plants, especially the seed-propagated ones, will develop the characteristic stout and swollen trunk at the crown called caudex that becomes larger with age, each individual uniquely shaped and no two plants are identical in shape and structure. Absolutely amazing!
  
  It bears glossy and leathery dark-green leaves (even variegated leaves are seen now) that are spirally arranged and clustered at terminal stems, of variable shapes and sizes – some lanceolate and tapering, others are obovate and bluntly tipped, ranging 5-15cm long and 1-8cm broad. A semi-deciduous shrub with leaves falling, sometimes completely defoliated, depending on the climatic conditions, moisture stress or care received. Nonetheless, new leaves will re-emerge as easily on extended growth with tender loving care!
  Attractive 5-petaled bell-shaped or tubular flowers of varying sizes are borne at stem tips, in clusters of 3 or more. Some hybrids even have double flowers. Flower colors previously were toned pink to red with a whitish blush radiating outwards from the throat or reddish-pink to white suffused with pink. Now, with the extensive hybridization of Desert Rose in China, Taiwan and Thailand, there is a wide range of exotic color combination, variegation and pattern – in varying hues, either pure or bicolor, from white to cream, light to dark pink and magenta, or rose-red to very deep red, orange and even purple. Some petals are even ruffled or sharp-pointed and even lily-like. Really exclusive!
  Desert Rose also yields apple-green bean-like seed pods that are thin and long, containing seeds that are used for propagation. Blooms of unrelated plants have to be pollinated by the Oleander Hawk Moth for a seed pod to develop.
  Properly cared, the medium to large conventional-sized shrubs especially, will be excellent producers of abundant flowers year round.

• Culture (Care): An easy-to-grow succulent plant that needs minimal attention. Nevertheless, with the right care, it not only gets larger and more spectacular, but more valuable each year. A large and older multi-branched specimen with lots of flowers and a huge caudex can cost a ‘bomb’ at our local garden centers!
  Light: Full sun or bright light for best growth and flowering, but can take to light shade or filtered sunlight. It is happiest with sufficient warmth, sunlight and fresh air.
  Moisture: Moderate water regularly. It needs more water during hot weather but avoid over-watering as it is prone to root rot. On the other hand, insufficient water can cause leaves to fall. Allow soil to dry completely between waterings. It is drought resistant in cooler weather. Some subspecies are known to flower abundantly with period of dryness following period of wetness.
  Soil: Any garden or potting soil with a mixture of coarse sand, crushed granite, gravel or brick chips that is free draining yet able to hold moisture and nutrients.
  Others: Desert Rose are heavy feeders. Feed fortnightly or once monthly during growth with a water-soluble fertilizer at half-strength. Using a phosphorus-based fertilizer, together with a good-draining media in a pot-bound container will most certainly increase caudex formation and enlargement. Even varying between moist and dry periods can help caudex development. When plant has outgrown its pot size, transplant it to a slightly larger container, planting it slightly above the previous soil level to expose more of its bulbous caudex and roots, providing room for their expansion above ground. Nonetheless, it can tolerate being pot-bound. Start styling the plant when young by pruning the new shoots regularly to encourage multi-branching. More branches mean more flowers! Do this by either removing the smallest two leaves at the tip or cut an inch or more from the tip of the stem, be careful though to avoid contact with the poisonous milky sap that can cause skin allergies. To maintain its attractiveness, best to also prune off any small roots emerging from the caudex region but not those fine feeder roots below the caudex. Watch out for caterpillars, mealy bugs and mites that can destroy or retard its growth and flowering.
  For subtropical and temperate regions: Hardiness: USDA Zone 10a-11 Check info at Dave’sGarden and read what other growers/lovers of Desert Rose have to say. Water sparingly during winter months but increase water during active growing and blooming in hot seasons.

• Propagation: By seed, stem cuttings or air-layering, though numerous hybrids are propagated mainly by grafting onto seedling rootstock. Seed-grown plants will easily develop the characteristic fat swollen trunks (claudex) that cutting-grown plants rarely will achieve. Seeds scattered into a mixture of sand and soil germinate easily. For propagation by stem cuttings, cut end shoots being mindful of the toxic sap, and allow them to dry for 2-3 days before planting them into a potting mixture of sand-peat, and keep the soil moist.

• Usage: Adenium obesum makes excellent container plant, any kind whether plastic, ceramic or clay pots is ideal. The shrub can be grown in the ground too as an ornamental standard specimen. Some hybrids or cultivars can be grown as Bonsai. The dwarf hybrids can be located indoors as houseplants if grown by a window, receiving sufficient heat, sunlight and ventilation. In some regions, the highly toxic sap of the plant is used as arrow poison for hunting and known traditionally too for its medicinal properties. More info at PROTA site.

Other external links:

• The best Adenium Site by far, presenting comprehensive insights on its culture, species, propagation, hybridization, and gallery of cultivars. A must read if you’re serious in getting your Desert Rose to be in top form!
• Desert Rose Info Page, University of Wisconsin
• mgonline’s photo collection of exotic hybrids
• Photo gallery of TopTropicals’ Thai Adenium hybrids
• KingAdenium Thailand, producer and exporter of Adenium obesum plants and seeds. Be astounded by its photo gallery of numerous exotic varieties, seldom seen before

Enjoy more images of Adenium obesum:

Last edited: June 5, 2010

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Tags: flowering plants, indoor plants, orange, outdoor plants, perennials, pink, red, shrubs, white