Melia azedarach

Abstract

DISTRIBUTION: Originally from Asia, now to be found all over southern Africa where it has been planted in gardens and on pavements in suburbs. It has become naturalised, especially along roadsides and stream banks and is declared an alien invasive tree, which has to be eradicated.

BOTANICAL PRINCIPLE: General: It is a deciduous, exotic invading tree that can grow up to 20 m in height, has a thick trunk and spreading branches. On the younger stems the bark is smooth with a distinctive reddish brown colour. Leaves: The deep green glossy leaves are twice compound with the leaflets up to 4 cm long. They turn yellow in autumn. Flowers: Blueish mauve fragrant sprays.Spring. Fruit: Masses of berries are produced. Green at first, turning yellow and wrinkled when ripe. Ripe fruit a woody pip with 5 parallel ridges. They remain on the trees for a long time after the leaves have fallen.

TOXIC PRINCIPLE: • The ripe fruits are more poisonous than the green berries or other parts of the plant. • Fortunately they are highly unpalatable to most animals and are seldom eaten. • The active principles are meliatoxins.

SYSTEMS AFFECTED: Central nervous system.

CLINICAL SIGNS: • The berries have caused poisoning in a variety of animals including ruminants and dogs, but pigs are the most prone to poisoning. • Chickens are not very susceptible to the toxin. • The signs of poisoning in pigs are: vomiting; respiratory distress and nervous signs. • Should they survive they become lame, particularly in the hindquarters, and develop diarrhoea.

NECROPSY: • Characteristic fruits and pips in the gastroinestinal tract. • Pip is woody with 5 parallel ridges.

TREATMENT: • Symptomatic • Cattle: Rumenotomy can be considered.