This plant can withstand severe droughts and has a strong root system that can extract nutrients and moisture from poor soils.
by Lalith Gunasekera
Botanical name: AZADIRACHTA INDICA
Common names: veppai (Tamil), kohomba (Sinhalese), margosa, neem tree (English), sadao (Thai), tamar (Burma), neem (Nepal), nim (Bengali), neeb ( Arabic)
( January 17, 2017, Melbourne, Sri Lanka Guardian) Kohoma tree is native to South East Asia including Sri Lanka, India, Pakistan, Thailand, Malaysia and Indonesia. However the tree is now grown in many parts of the world including Florida and Arizona in the United States.
Kohomba is a fast growing tree, generally 15-20 meters tall (sometimes up to 40 m tall), with a crown diameter up to 20 m. This plant is evergreen but can shed most of its leaves under dry conditions. The compound leaves are alternate, 20-40 cm long with 20-30 dark green, serrated leaflets each about 3-8 cm long. The terminal leaflet is often absent. Young leaves are reddish to purplish in colour. Leaf petioles are 70 – 90 mm long.
Kohomba flowers are white, small, honey scented and grow in sprays up to 30 cm long and comprises 150-250 individual flowers. Each flower is about 1 cm in diameter with five petals. The flowers are pollinated by bees and other insects. Male and female flowers are produced on the same tree. Fruiting starts when plants are 2-5 years old and reaches full production at 10-15 years of age. The fruit has a thin layer of flesh and varies in shape from elongate oval to nearly roundish with one internal seed, is about 1-2 cm long, and is green turning yellow when ripe. It is estimated that a well grown plant produces over 50, 000 – 200000 seeds each year in North Queensland.
Seeds germinate readily around the parent plant. Seed is dispersed further mainly when ingested and expelled by birds and animals.
This plant can withstand severe droughts and has a strong root system that can extract nutrients and moisture from poor soils. The taproot of this tree is nearly twice the height of the tree and a girth of tree can grow up to 2.5 meters. Suckers can be produced following damage to the roots. Kohomba tree can live up to 200 years.
This drought tolerant species is grown to prevent soil erosion and to help in soil conservation and improvement. Kohomba improves soil fertility and water holding capacity and can neutralise acidic soils and so is used for the reclamation of degraded land.
The wood is hard and resistant to termites, borers and fungi. Kohomba is considered suitable for general purpose plywood, fire retardant plywood and plywood for blackboard.
In Ayurveda “Kohomba tree has been described as “ sarva roga nivarani” (keep all diseases at bay). The plant extracts have been used in the Ayurvedic tradition for thousands of years for maintaining health and overall wellbeing. The roots, bark, gum, leaves, fruit, seed, kernels and seed oil are all used in therapeutic preparations for internal and topical use.
• Kohomba leaf has antifungal and antibacterial properties, making it effective in treating dandruff.
• It also relieves dryness and itching, strengthens hair and promotes hair growth.
• Kohomba is mentioned in most Ayurvedic formulations for the treatment of skin disorders because of its detoxifying properties.
• Kohomba oil and leaves are excellent skin care ingredients. The oil relieves dry skin and soothes itchiness, redness and irritation.
• The antibacterial qualities of Kohomba make it ideal for eliminating the bacteria beneath the gums that causes periodontal disease and halitosis (bad breath). Kohoma is popular in mouthwashes and toothbrushes due to that reason.
• Kohomba soap is made from the oil extracted from the fruits and seeds of kohomba plant. In India, 80% of all kohomba oil is used for making soap. The soap is a real treat for the skin even for healthy skin. Some soaps have kohomba leaf extract added. Both oil and leaf are great ingredients for any skin care products. Infact, a soap that contains both would be excellent.
Kohomba is invasive plant and serious problem in parts of Kenya, Tanzania and Uganda especially in coastal areas.
Kohomba was heavily promoted by a few people in the 1980s in Australia (Queensland, Northern Territory, Western Australia) and enthusiastically planted by many more, a viable industry does not seem to have developed and many plantations have been abandoned.
Reports of kohomba starting to grow wild in Queensland have occurred since early 1990s. Most spread appears to be occurring in the Gulf region of North West Queensland.
Listing of a species as a weed does not necessarily mean that it is a significant problem. It may simply be a ruderal species, restricted to roadsides, abandoned farmland and other highly disturbed sites rather than actually interfering with primary production, native values or human health.
( Dr. Lalith Gunasekera is an invasive Plants Specialist based in Mackay – Queensland )