NEEM Azadirachta indica Meliaceae
San: Nimbah, Prabhadrah Hin, Ben: Nim, Nim Mal: Aryaveppu Tel: Vepa Ori: Nimba
Tam: Vembu, Veppu Pun: Bakam,Bukhain Guj: Limba Kan: Bevu Mar: Limbu
Importance
Neem or margose tree, also known as Indian lilac is a highly exploited medicinal
plant of Indian origin, widely grown and cultivated throughout India. Every part of the tree,
namely root, bark, wood, twig, leaf, flower, fruit, seed, kernel and oil has been in use from
time immemorial in the Ayurvedic and Unani systems of medicine. Nimbarishta, nimbadi
churna and nimbharidra khand are well known preparations. It is valuable as an antiseptic,
used in the treatment of small pox. Small twigs are used as tooth brushes and as a
prophylactic for mouth and teeth complaints. Extract from the leaves are useful for sores,
eczema and skin diseases. Boiled and smashed leaves serve as excellent antiseptic.
Decoction of leaves is used for purifying blood. Neem oil is used in soaps, toothpaste and as
a hair tonic to kill lice. Seed is used in snake bite. The fruits and leaves being renewable,
provide sustainable returns. Different parts of the fruit are separated into components and
each one produces derivatives of varying chemical nature and utility. Neem derivatives are
now used in agriculture, public health, human and veterinary medicines, toiletries, cosmetics
and livestock production. Applications as pesticides, allied agrochemicals, plant nutrients
and adjuvants for improving nitrogen use efficiency are of much importance. Neem kernel
suspension (1%) is a house hold insecticide. Pesticide formulations containing azadirachtin
are now commercially available in India, USA, Canada, Australia and Germany. Neem cake
is rich in N, P, K, Ca and S. Neem Meliacins like epinimbin and nimbidin are commercially
exploited for the preparation of slow and extended release of nutrients including nitrification
inhibitors (Eg. Nimin). Extracts of neem seed oil and bark check the activity of male
reproductive cells and prevents sperm production. Neem seed oil is more effective than the
bark for birth control. Neem based commercial products are also available for diabetes
treatment (Nimbola, JK-22), contraceptive effect (Sensal, Nim-76) and mosquito/ insect
repelling (Srivastava, 1989; Tewari, 1992; Parmer and Katkar, 1993; Pushpangadan et al,
1993; Mariappan, 1995).
Distribution
Neem is a native of the Siwalik deccan parts of South India. It grows wild in the dry
forests of Andra Pradesh, Tamil Nadu and Karnataka. It has spread to Pakistan, Bangladesh ,
Sri Lanka, Malaysia, Indonesia, Thailand, Middle East Sudan and Niger. It is now grown in
Australia, Africa, Fiji, Mauritious, Central and South America, the Carribeans, Puerto Rico
and Haiti. The largest known plantation of nearly 50,000 trees is at Arafat plains en route to
Mecca in Saudi Arabia for providing shade to Haj pilgrims (Ahmed, 1988).
Botany
The genus Azadirachta of family Meliaceae comprises two species: A. indica A. Juss
syn. Melia azadirachta Linn. and A. excelsa (Jack) Jacobs syn. A. integrifolia Mers., the
latter being found in Philippines, Sumatra, Malaya, Borneo and New Guinea. Neem is a hardy
medium to large, mostly evergreen tree attaining 20m height and 2.5m girth. It has a short bole
with wide spreading branches and glabrous twigs forming a round to oval crown. The bark is
thick, dark-gray with numerous longitudinal furrows and transverse cracks. Leaves are
imparipinnately compound, alternate, exstipulate and 20-38cm long. Inflorescence is long,
slender, axillary or terminal panicle. Flowers are white or pale yellow, small, bisexual,
pentamerous and bracteate. Stamens 10; filaments unite to form a moniliform tube. Gynoecium
is tricarpellary and syncarpous, ovary superior, trilocular. Each carpel bears two collateral
ovules on parietal placentation. Fruit is one seeded drupe with woody endocarp, greenish
yellow when ripe. Seed ellipsoid, cotyledons thick fleshy and oily. Neem has chromosome
number 2n = 28. Neem trees tend to become deciduous for a brief period in dry ecology.
Ecotypes, exhibiting morphological variation in root growth, leaf size, contents, bole length ,
canopy, inflorescence, fruit bearing, seed size, shape and quality exist in natural populations.