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Friday, April 3, 2009

Melia azedarach

Commonly called Persian Lilac, White Cedar, Chinaberry or Bead Tree, Melia azedarach(syn. M. australis, M. japonica, M. sempervivens), is a deciduous tree in the mahogany family Meliaceae, native to India, southern China and Australia. In South Africa it is commonly but erroneously called Syringa, which is in fact the lilac genus. The genus Melia includes four other species, occurring from southeast Asia to northern Australia. They are all deciduous or semi-evergreen trees.
Indian Grey Hornbill Ocyceros birostris eating its fruit at Roorkee in Haridwar District of Uttarakhand, India.

The adult tree has a rounded crown, and measures between 7 and 12 metres in height. The flowers are small and fragrant, with five pale purple or lilac petals, growing in clusters. The fruit is a drupe, marble-sized, light yellow at maturity, hanging on the tree all winter, and gradually becoming wrinkled and almost white. In Australian rainforests, Melia azedarach can attain a height of 45 metres.
leaves & green fruit in Kolkata, West Bengal, India.

The leaves are up to 50 cm long, alternate, long-petioled, 2 or 3 times compound (odd-pinnate); the leaflets are dark green above and lighter green below, with serrate margins. They have been used as a natural insecticide to keep with stored food, but must not be eaten as they are highly poisonous. A diluted infusion of leaves and trees has been used in the past to induce uterus relaxation.


Uses and ecology

The main utility of chinaberry is its timber. This is of medium density, and ranges in colour from light brown to dark red. In appearance it is readily confused with the unrelated Tectona grandis (Burmese Teak). Melia azedarach in keeping with other members of the family Meliaceae has a timber of high quality, but as opposed to many almost-extinct species of mahoganys it is under-utilised. Seasoning is relatively simple in that planks dry without cracking or warping and are resistant to fungal infection. Also known as Ghoda neem (Ghoda meaning horse) in Bengali and Vilayati (foreign) neem in Bundelkhand region, Dharek in Punjab region and Bakain in East Uttar Pradesh and Jharkhand region of India. The taste of the leaves are not so bitter as Neem (Azaderachta indica).

The hard, 5-grooved seeds were widely used for making rosaries and other products requiring beads, before their replacement by modern plastics.

The flowers are unattractive to bees and butterflies. Though some hummingbirds like Sapphire-spangled Emerald (Amazilia lactea), Glittering-bellied Emerald (Chlorostilbon lucidus) and Planalto Hermit (Phaethornis pretrei) have been recorded to feed on and pollinate the flowers, these too only take it opportunistically.

Toxicity

Fruits are poisonous to humans if eaten in quantity. However, like the Yew tree, these toxins are not harmful to birds, who gorge themselves on the fruit, eventually reaching a "drunken" state. The toxins are neurotoxins and unidentified resins, found mainly in the fruits. Some birds are able to eat the fruit, spreading the seeds in their droppings. The first symptoms of poisoning appear a few hours after ingestion. They may include loss of appetite, vomiting, constipation or diarrhea, bloody faeces, stomach pain, pulmonary congestion, cardiac arrest, rigidity, lack of coordination and general weakness. Death may take place after about 24 hours. Like in relatives, tetranortriterpenoids consititute an important toxic principle. These are chemically related to Azadirachtin, the primary insecticidal compound in the commercially important Neem oil. These compounds are probably related to the wood and seed's resistance to pest infestation, and maybe to the unattractiveness of the flowers to animals.

As invasive species

The plant was introduced around 1830 as an ornamental in the United States (South Carolina and Georgia) and widely planted in southern states. Today it is considered an invasive species by some groups as far north as Virginia and Oklahoma. But nurseries continue to sell the trees, and seeds are also widely available. It has become naturalized to tropical and warm temperate regions of the Americas and is planted in similar climates around the world. Besides the problem of toxicity, its usefulness as a shade tree in urban areas is diminished by its tendency to sprout where unwanted and to turn sidewalks into dangerously slippery surfaces when the fruits fall, though this is not a problem where songbird populations are in good shape. As noted above, the possibility of commercially profitable over-exploitation of feral stands remains largely unexplored.

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