Azadirachta indica, also known as Neem, Nimtree, and Indian Lilac is a tree in the mahogany family Meliaceae. It is one of two species in the genus Azadirachta, and is native to India and the Indian subcontinent including Nepal, Pakistan, Bangladesh and Sri Lanka. Typically growing in tropical and semi-tropical regions. Neem trees now also grow in islands in the southern part of Iran. Its fruits and seeds are the source of neem oil.
Neem is a fast-growing tree that can reach a height of 15–20 metres (49–66 ft), rarely to 35–40 metres (115–131 ft). It is evergreen, but in severe drought it may shed most or nearly all of its leaves. The branches are wide and spreading. The fairly dense crown is roundish and may reach a diameter of 15–20 metres (49–66 ft) in old, free-standing specimens. The neem tree is very similar in appearance to its relative, the Chinaberry (Melia azedarach).
The opposite, pinnate leaves are 20–40 centimetres (7.9–15.7 in) long, with 20 to 31 medium to dark green leaflets about 3–8 centimetres (1.2–3.1 in) long. The terminal leaflet is often missing. The petioles are short.
The (white and fragrant) flowers are arranged in more-or-less drooping axillary panicles which are up to 25 centimetres (9.8 in) long. The inflorescences, which branch up to the third degree, bear from 150 to 250 flowers. An individual flower is 5–6 millimetres (0.20–0.24 in) long and 8–11 millimetres (0.31–0.43 in) wide. Protandrous, bisexual flowers and male flowers exist on the same individual tree.
The fruit is a smooth (glabrous) olive-like drupe which varies in shape from elongate oval to nearly roundish, and when ripe is 1.4–2.8 centimetres (0.55–1.10 in) by 1.0–1.5 centimetres (0.39–0.59 in). The fruit skin (exocarp) is thin and the bitter-sweet pulp (mesocarp) is yellowish-white and very fibrous. The mesocarp is 0.3–0.5 centimetres (0.12–0.20 in) thick. The white, hard inner shell (endocarp) of the fruit encloses one, rarely two or three, elongated seeds (kernels) having a brown seed coat.
Neem is a Hindi noun derived from Sanskrit Nimba.
The neem tree is noted for its drought resistance. Normally it thrives in areas with sub-arid to sub-humid conditions, with an annual rainfall 400–1,200 millimetres (16–47 in). It can grow in regions with an annual rainfall below 400 mm, but in such cases it depends largely on ground water levels. Neem can grow in many different types of soil, but it thrives best on well drained deep and sandy soils. It is a typical tropical to subtropical tree and exists at annual mean temperatures between 21–32 °C (70–90 °F). It can tolerate high to very high temperatures and does not tolerate temperature below 4 °C (39 °F). Neem is one of a very few shade-giving trees that thrive in drought-prone areas e.g. the dry coastal, southern districts of India and Pakistan. The trees are not at all delicate about water quality and thrive on the merest trickle of water, whatever the quality. In India and tropical countries where the Indian diaspora has reached, it is very common to see neem trees used for shade lining streets, around temples, schools & other such public buildings or in most people’s back yards. In very dry areas the trees are planted on large tracts of land.
Neem is considered a weed in many areas, including some parts of the Middle East, and most of Sub-Saharan Africa including West Africa and Indian Ocean states. Ecologically, it survives well in similar environments to its own, but its weed potential has not been fully assessed.
Neem leaves are dried in India and placed in cupboards to prevent insects eating the clothes and also while storing rice in tins. Neem leaves are dried and burnt in the tropical regions to keep away mosquitoes. These leaves are also used in many Indian festivals like Ugadi. See below: #Association with Hindu festivals in India. As Ayurveda herb, Neem is also used in baths.
As a vegetable
The tender shoots and flowers of the neem tree are eaten as a vegetable in India. A souplike dish called Veppampoo charu (Tamil) (translated as “neem flower rasam”) made of the flower of neem is prepared in Tamil Nadu. In West Bengal, young neem leaves are fried in oil with tiny pieces of eggplant (brinjal). The dish is called nim begun and is the first item during a Bengali meal that acts as an appetizer. It is eaten with rice.
Neem is used in parts of mainland Southeast Asia, particularly in Cambodia aka sdov, Laos (where it is called kadao), Thailand (where it is known as sadao or sdao), Myanmar (where it is known as tamar) and Vietnam (where it is known as sầu đâu and is used to cook the salad gỏi sầu đâu). Even lightly cooked, the flavour is quite bitter and the food is not enjoyed by all inhabitants of these nations, though it is believed to be good for one’s health. Neem gum is a rich source of protein. In Myanmar, young neem leaves and flower buds are boiled with tamarind fruit to soften its bitterness and eaten as a vegetable. Pickled neem leaves are also eaten with tomato and fish paste sauce in Myanmar.
Traditional medicinal use
Products made from neem trees have been used in India for over two millennia for their medicinal properties. Neem products are believed by Sidha and Ayurvedic practitioners to be anthelmintic, antifungal, antidiabetic, antibacterial, antiviral, contraceptive and sedative. It is considered a major component in sidha medicine and Ayurvedic and Unani medicine and is particularly prescribed for skin diseases. Neem oil is also used for healthy hair, to improve liver function, detoxify the blood, and balance blood sugar levels. Neem leaves have also been used to treat skin diseases like eczema, psoriasis, etc.
However, insufficient research has been done to assess the purported benefits of neem. In adults, short-term use of neem is safe, while long-term use may harm the kidneys or liver; in small children, neem oil is toxic and can lead to death. Neem may also cause miscarriages, infertility, and low blood sugar.
Neem oil can cause some forms of toxic encephalopathy and ophthalmopathy if consumed in large quantities.
Pest and disease control
Neem is a key ingredient in non-pesticidal management (NPM), providing a natural alternative to synthetic pesticides. Neem seeds are ground into a powder that is soaked overnight in water and sprayed onto the crop. To be effective, it is necessary to apply repeatedly, at least every ten days. Neem does not directly kill insects on the crop. It acts as an anti-feedant, repellent, and egg-laying deterrent, protecting the crop from damage. The insects starve and die within a few days. Neem also suppresses the hatching of pest insects from their eggs. Neem cake is often sold as a fertilizer.
Neem oil has been shown to avert termite attack as ecofriendly and economical agent.
The twigs are also used as tooth brush. One end is chewed to turn it into soft bristles to clean the teeth by brushing.
Toiletries: Neem oil is used for preparing cosmetics such as soap, shampoo, balms and creams as well as toothpaste.
Toothbrush: Traditionally, slender neem twigs (called datun;) are first chewed as a toothbrush and then split as a tongue cleaner. This practise has been in use in India, Africa, and the Middle East for centuries. Many of India’s 80% rural population still start their day with the chewing stick, while in urban areas neem toothpaste is preferred. Neem twigs are still collected and sold in markets for this use, and in rural India one often sees youngsters in the streets chewing on neem twigs. It has been found to be equally effective as a toothbrush in reducing plaque and gingival inflammation.
Tree: Besides its use in traditional Indian medicine, the neem tree is of great importance for its anti-desertification properties and possibly as a good carbon dioxide sink.
Neem gum is used as a bulking agent and for the preparation of special purpose foods.
Neem blossoms are used in Andhra Pradesh, Tamil Nadu and Karnataka to prepare Ugadi pachhadi. A mixture of neem flowers and jaggery (or unrefined brown sugar) is prepared and offered to friends and relatives, symbolic of sweet and bitter events in the upcoming new year, Ugadi. “Bevina hoovina gojju” (a type of curry prepared with neem blossoms) is common in Karnataka throughout the year. Dried blossoms are used when fresh blossoms are not available. In Tamil Nadu, a rasam (veppam poo rasam) made with neem blossoms is a culinary specialty.
Cosmetics : Neem is perceived in India as a beauty aid. Powdered leaves are a major component of at least one widely used facial cream. Purified neem oil is also used in nail polish and other cosmetics.
Bird repellent: Neem leaf boiled in water can be used as a very cost effective bird repellent, especially for sparrows.
Lubricant : Neem oil is non drying and it resists degradation better than most vegetable oils. In rural India, it is commonly used to grease cart wheels.
Fertilizer : Neem has demonstrated considerable potential as a fertilizer. Neem cake is widely used to fertilize cash crops, particularly sugarcane and vegetables. Ploughed into the soil, it protects plant roots from nematodes and white ants, probably as it contains the residual limonoids. In Karnataka, people grow the tree mainly for its green leaves and twigs, which they puddle into flooded rice fields before the rice seedlings are transplanted.
Resin : An exudate can be tapped from the trunk by wounding the bark. This high protein material is not a substitute for polysaccharide gum, such as gum arabic. It may however, have a potential as a food additive, and it is widely used in South Asia as “Neem glue”.
Bark : Neem bark contains 14% tannin, an amount similar to that in conventional tannin yielding trees (such as Acacia decurrens). Moreover, it yields a strong, coarse fibre commonly woven into ropes in the villages of India.
Honey : In parts of Asia neem honey commands premium prices, and people promote apiculture by planting neem trees.
Soap : 80% of India’s supply of neem oil is now used by neem oil soap manufacturers. Although much of it goes to small scale speciality soaps, often using cold-pressed oil, large scale producers also use it, mainly because it is cheap. Additionally it is antibacterial and antifungal, soothing and moisturising. It can be made with up to 40% neem oil. Well known brands include Margo. Generally, the crude oil is used to produce coarse laundry soaps.
Association with Hindu festivals in India
Neem leaf or bark is considered an effective pitta pacifier due to its bitter taste. Hence, it is traditionally recommended during early summer in Ayurveda (that is, the month of Chaitra as per the Hindu Calendar which usually falls in the month of March – April).
In the Indian states of Andhra Pradesh and Karnataka, Neem flowers are very popular for their use in ‘Ugadi Pachhadi’ (soup-like pickle), which is made on Ugadi day. In Karnataka, a small amount of Neem and Jaggery (Bevu-Bella) is consumed on Ugadi day, the Kannada new year, indicating that one should take both bitter and sweet things in life, joy and sorrow.
During Gudi Padva, which is the New Year in the state of Maharashtra, the ancient practice of drinking a small quantity of neem juice or paste on that day, before starting festivities, is found. As in many Hindu festivals and their association with some food to avoid negative side-effects of the season or change of seasons, neem juice is associated with Gudi Padva to remind people to use it during that particular month or season to pacify summer pitta.
In Tamil Nadu during the summer months of April to June, the Mariamman temple festival is a thousand year old tradition. The Neem leaves and flowers are the most important part of the Mariamman festival. The goddess Mariamman statue will be garlanded with Neem leaves and flowers. During most occasions of celebrations and weddings the people of Tamil Nadu adorn their surroundings with the Neem leaves and flowers as a form of decoration and also to ward off evil spirits and infections.
In the eastern coastal state of Odisha the famous Jagannath temple deities are made up of Neem heart wood along with some other essential oils and powders.
Salimuzzaman Siddiqui was the first scientist to bring the anthelmintic, antifungal, antibacterial, and antiviral constituents of the Neem tree to the attention of natural products chemists. In 1942, he extracted three bitter compounds from neem oil, which he named as nimbin, nimbinin, and nimbidin respectively. The process involved extracting the water insoluble components with ether, petrol ether, ethyl acetate and dilute alcohol. The provisional naming was nimbin (sulphur-free crystalline product with melting point at 205 °C, empirical composition C7H10O2), nimbinin (with similar principle, melting at 192 °C), and nimbidin (cream-coloured containing amorphous sulphur, melting at 90–100 °C). Siddiqui identified nimbidin as the main active antibacterial ingredient, and the highest yielding bitter component in the neem oil. These compounds are stable and found in substantial quantities in the Neem. They also serve as natural insecticides.
Genome and transcriptomes
Neem genome and transcriptomes from various organs have been sequenced, analyzed and published by Ganit Labs in Bangalore, India.
Cultural and social impact
In Theravada Buddhism, Neem tree is said to have used as the tree for achieved enlightenment, or Bodhi by twenteeth Lord Buddha called “Tissa”. But in some text books, it is stated that Terminalia tomentosa is the Bodhi tree used by Tissa Lord Buddha.
In 1995, the European Patent Office (EPO) granted a patent on an anti-fungal product derived from neem to the US Department of Agriculture and W. R. Grace and Company. The Indian government challenged the patent when it was granted, claiming that the process for which the patent had been granted had actually been in use in India for over 2,000 years. In 2000, the EPO ruled in India’s favour but W. R. Grace appealed, claiming that prior art about the product had never been published in a scientific journal. On 8 March 2005, that appeal was lost and the EPO revoked the Neem patent.