Botanical Name:Adenium obesum
Synonyms: Adenium somalense Balf.f. (1888), Adenium socotranum Vierh.
Common Name:Sabi Star, Kudu or Desert-rose.Due to its resemblance to plumeria, and the fact that it was introduced to the Philippines from Bangkok, Thailand, the plant was also called as Bangkok kalachuchi in the Philippines.
Species: A. obesum
Habitat:It is native to tropical and subtropical eastern and southern Africa and Arabia.(Eastern Africa to southern Arabia)
Succulent shrub or small tree, up to 4(–6) m tall, sometimes with a fleshy taproot; stem swollen at base up to 1(–2) m in diameter; bark pale greyish-green, grey or brown, smooth, with sticky, clear or white latex; branchlets glabrescent, pubescent at apex. Leaves arranged spirally, clustered at the end of branchlets, simple; stipules minute or absent; petiole up to 4 mm long; blade linear to obovate, 3–12(–17) cm × 0.2–6 cm, base cuneate, apex acute to rounded or emarginate, entire, slightly glaucous, dull green or pale green, leathery, pinnately veined with distinct or indistinct lateral veins. Inflorescence a more or less dense terminal cyme; bracts linear to narrowly oblong, 3–8 mm long, acuminate, pubescent. Flowers bisexual, regular, 5-merous, showy, usually appearing before the leaves; pedicel 5–9 mm long; sepals narrowly oblong to narrowly ovate, 6–12 mm long, hairy; corolla with funnel-shaped tube 2–4.5 cm × 0. 9–1.7 cm, reddish-pink to white suffused with pink, sometimes red-striped inside the throat, hairy to glabrous outside, glandular hairy on main veins inside, lobes 1–3 cm × 0.5–2.5 cm, spreading, pale pink to red with darker margins; stamens inserted near base of corolla tube, included or exserted, anthers forming a cone covering the pistil, base sagittate, 5–7 mm long, with long apical appendices; ovary superior, composed of 2 free carpels, glabrous, styles fused, slender, with well-developed clavuncula. Fruit consisting of 2 linear-oblong follicles, coherent at the base, 11–22 cm long, tapering at both ends, recurved, grey to pale grey-brown, opening by a longitudinal slit, many-seeded. Seeds linear-oblong, 10–14 mm long, pale brown, slightly rough, with tufts of long dirty white hairs at both ends.
Adenium is a genus of flowering plants in the family Apocynaceae, containing a single species, Adenium obesum, also known as Sabi Star, Kudu or Desert-rose.
It is an evergreen succulent shrub in tropical climates and semi-deciduous to deciduous in colder climates, is also dependent on the subspecies or cultivar. Growing to 1–3 m in height, with pachycaul stems and a stout, swollen basal caudex. The leaves are spirally arranged, clustered toward the tips of the shoots, simple entire, leathery in texture, 5–15 cm long and 1–8 cm broad. The flowers are tubular, 2–5 cm long, with the outer portion 4–6 cm diameter with five petals, resembling those of other related genera such as Plumeria and Nerium. The flowers tend to red and pink, often with a whitish blush outward of the throat.Classification
Cultivation and uses
Adenium is a popular houseplant in temperate regions. It requires a sunny location and a minimum indoor temperature in winter of 10 °C. It thrives on a xeric watering regime as required by cacti. Adenium is typically propagated by seed or stem cuttings. The numerous hybrids are propagated mainly by grafting onto seedling rootstock. While plants grown from seed are more likely to have the swollen caudex at a young age, with time many cutting-grown plants cannot be distinguished from seedlings.
The plant exudes a highly toxic sap which is used by some peoples, such as the Akie and Hadza in Tanzania, to coat arrow-tips for hunting.
Propagation: Cuttings, seeds
In Adenium obesum the presence of some 30 cardiotoxic glycosides has been demonstrated, which act in a similar way as digitalis from Digitalis. Digitalis acts upon the Na+K+-ATPase enzyme that regulates the concentrations of Na+ and K+ ions in body cells and so also modifies the Ca++ concentration. In low doses it is used to treat congestive heart failure (CHF) and heart rhythm problems (atrial arrhythmias), but in high doses it leads to systolic heart failure and death.
Several of the cardiac glycosides from Adenium obesum have oleandrigenin as aglycone moiety, e.g. hongheloside A (with D-cymarose), hongheloside C (with D-cymarose and D-glucose) and 16-acetylstrospeside (with D-digitalose). Other glycosides include: hongheline (composed of digitoxigenin with D-thevetose), somaline (composed of digitoxigenin with D-cymarose) and digitalinum verum (composed of gitoxigenin with D-digitalose and D-glucose). The roots and stems contain the same glycosides and in similar amounts. Oleandrigenin and some of the glycosides derived from it have cytotoxic effects and are being studied as potential components of anticancer drugs.
The ethanol extract of the roots slows down the growth of Bacillus subtilis, but has not shown activity against Pseudomonas aeruginosa, Staphylococcus aureus or Candida albida. Extracts from the root have shown a cytotoxic effect against several carcinoma cell lines. The aqueous stem bark extract is a potential acaricide as it shows high toxicity on all stadia of development of the ticks Amblyomma spp. and Boophilus spp.
In a wide area of Africa the root sap or sometimes the wood or stem latex of Adenium obesum is used to prepare arrow poison. The poison is popular for hunting large game as it kills quickly and the hunted animal dies within 2 km from the place where it was shot. The Hadza people of Tanzania use the sap by itself or sometimes in combination with poison from Strophanthus eminii Asch. & Pax, while the Duruma people of Kenya use the stem latex, sometimes in combination with the roots and wood of Acokanthera schimperi (A.DC.) Schweinf. or the latex of Synadenium pereskiifolium (Baill.) Guillaumin. The use of Adenium obesum arrow poison is also reported from Senegal, Nigeria and Cameroon. A decoction of the bark and leaves is widely used as fish poison. This use is reported from Nigeria, Cameroon and East Africa. In Mauritania and Senegal preparations from Adenium obesum are used as ordeal poison and for criminal purposes.
Adenium obesum is important in traditional medicine. In the Sahel a decoction from the roots, alone or in combination with other plants, is used to treat venereal diseases; a root or bark extract is used as a bath or lotion to treat skin diseases and to kill lice, while latex is applied to decaying teeth and septic wounds. In Somalia a root decoction as nose drops is prescribed for rhinitis. In northern Kenya latex is rubbed on the head against lice and powdered stems are applied to kill skin parasites of camels and cattle. The bark is chewed as an abortifacient.
Adenium obesum is planted fairly frequently for its curious form and attractive flowers. Sometimes it is planted as a live fence. In Tanzania it is planted to mark the position of graves. The wood is sometimes used as fuel.
The genus Adenium has been held to contain as many as twelve species. These are considered by other authors to be subspecies or varieties. A late-20th-century classification by Plazier recognizes five species.
A partial list of regional species/subspecies/varieties are:
Adenium obesum subsp. boehmianum. Namibia, Angola.
Adenium obesum subsp. obesum. Arabia.
Adenium obesum subsp. oleifolium. South Africa, Botswana.
Adenium obesum subsp. socotranum. Socotra.
Adenium obesum subsp. somalense. Eastern Africa.
Adenium obesum subsp. swazicum. Eastern South Africa.
Adenium obesum subsp. arabicum. Arabia.
Adenium multiflorum. Southern Africa, from Zambia south
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