Chapter 1 - Botanical characteristics

Neem

Azadirachta Indica is a fast growing plant that usually reaches a height of 15-20m, and under very favourable conditions upto approximately 30-35. As a rule it is an evergreen tree, but under extreme circumstances, such as extended dry periods, it may shed most or nearly all of its leaves. The branches spread widely. The fairly dense crown is roundish or oval and may reach a diameter 15-20m in old, free standing specimens.

The trunk is relatively short, stright and may reach a girth of 1.5 - 3.5 m. The bark is hard, fissured or scaly planet and whitish-gray to reddish-brown. The sap wood is graylish-white and the heart wood reddish when first exposed to the air, be coming reddish-brown after exposure. The root system consists of a strong taproot and well developed lateral roots. The lateral surface roots may reach over 18m. Vesicular-arbuscular Mycorrhiza is associated with the rootlets; HABTE et al, categorized neem as a highly VAM dependant plant species.

The unpaired, pinnate leaves are 20-40 cm long and the medium to dark green leaflets which number upto 31, are approximatelty 3-8 cm long. The terminal leaflet is often missing. The petioles are short. Very young leaves are reddish to purplish in color. The shape of mature leaflets is more or less asymmetric and their margins are denate with the exception of the base of their basiscopal half, which is normally very strongly reduced and cuneate. The leaves contain 12.40 - 18.27% crude protein, 11.40 - 23.08% crude fiber, 43.32 - 66.60% N-free extract 2.27 - 6.24 ether extract, 7.73 - 18.37% total ash, 0.89 - 3.96% calcium and 9.10 - 0.30% phophorous.

Natural hybrids between indica and siamensis, found in Thailand on places where both species grow together have an intermediate position regarding the shape and consistency of the leaflets.

The white, fragrant flowers are arranged in axillary normally more or less dropping panicles which are up to 25 cm long. The inflorescences, which branch up to third degree, bear approximately 150, and occasionally up yo 250 flowers. An individual flower is 5-6mm long and 8-11 mm wide. The five petals are 5-5.5mm long and 2mm wide. Protandric bisexual flowers and male flowers exist on the same individual . Certain solitary growing neem trees seem to be unable to self-fertilization as observed in Nicaragua. Honeybees are important pollitaris in Africa, Asia and Australia in stringless bees in tropical America. The ovary is trilcoluar. There are ten glabrous anthers which are inserted at the base of the flowers. The nectary is annular and fused at the bases of the ovary.

The glabrous fruits are olive-like drupen which vary in shape from elongate oval to nearly roundish and when ripe are 1.4-2.8 * 1.0-1.5 cm. They are green when young and yellowish - green to yellow, rarely reddish when mature. The fruit skin is thin and bitter-sweep pulp is yellowish-white and very fibrous. The mesocarp is 0.3 - 0.5 cm thick. The white, hard 'shell' of the seed encloses one, rarely two and very rarely three eloganted seeds having a brown testa. The seeds measure 0.9-2.2 * 0.5-0.8 cm, and the 'seed kernals' are 0.8- 1.6 * 0.4-0.5 cm.

The number of chromosomes is : 2n=28, 30; n=14. The anatomy of the leaf, bark and wood as well as palynology and embryology are described in detail by TEWARI and are therefore not discussed here.

A. Indica may reach an age of more than 200 years.