Today, it is vilified as an invasive tree that causes enormous damage to the environment and inhibits the growth of indigenous plants. But in the early 1960s, when Tamil Nadu was reeling under a severe shortage of firewood and the issue even triggered a debate in the Legislative Assembly, prosopis Juliflora , known as seemai karuvelam , was seen as a saviour to overcome this shortage. It even earned the sobriquet panjam thaangi (providing succour during famine) .
The then Congress government, led by Chief Minister Kamaraj, made arrangements for aerial seeding of the plant from a helicopter in Ramanathapuram district. The authorities in other districts advised people to plant the tree in poromboke land, tank bunds and natham land to overcome the firewood shortage. The tree was also used to erect fences, making it difficult for animals to invade agricultural fields.
With cooking gas and kerosene replacing firewood even in remote villages, the role of seemai karuvelam as a provider of firewood has almost come to an end. But, the tree has entrenched itself in the soil, spreading its roots like the tentacles of a mythical animal.
The Jamaican connection
Though the plant gained popularity in the 1960s, seemai karuvelam actually arrived almost a century ago. According to the Food and Agriculture Organisation (FAO) of the United Nations, Lt. Col. R.H. Bendome, Conservator of Forests of Northern circle (Madras), was responsible for its introduction. He had requested the Secretary of the Revenue department of Madras to supply seeds of the plant for planting in arid tracts of South India in 1876.
The seeds were received from Jamaica and sown in South India during 1877.
Even in 1953, the Fodder and Grazing Committee of Madras decided to grow seemai karuvelam on a large scale on the slopes of barren hills and panchayat forests to augment fuel supply. In fact, The Hindu archives have an advertisement placed by a nursery in T. Nagar selling the tree’s seeds.
While various species of Prosopis were introduced at the time, P. juliflora has spread over large areas and has naturalised in most of the arid and semi-arid regions of India.
“ P. juliflora has survived where other tree species have failed, and in many cases, become a major nuisance. It has invaded, and continues to invade, millions of hectares of rangeland in South Africa, East Africa, Australia and coastal Asia. In 2004, it was rated one of the world’s top 100 least wanted species (Invasive Species Specialist Group of the IUCN, 2004),” wrote V. Nandagopalan, A. Doss and S.P. Anand of the PG and Research Department of Botany, National College in Tiruchi, in an article published in 2014 by the International Journal of Phytotherapy .
Preferred food for fauna
Dispersal of the species is mainly through animals by endozoochory (dispersal via ingestion by vertebrate animals). The pods are succulent and are a preferred choice of food for animals.
The FAO has reported that initially, the plant was observed to occur in areas of 150-750 mm annual rainfall. “However, invasions have been recorded in large ricegrowing stretches of Cauvery River Delta in Tamil Nadu State with mean annual rainfall of 1500 mm and where the occurrence of floods and inundation are common,” it adds.
The researchers of the National College, who had carried out their field study in Pudukkottai district, explained that an injury from the thorn of the species would not heal easily despite intensive medical treatments, and using the wood in a fireplace could also cause dermatitis. They also pointed to the available reports on cattle toxicity.
“According to reports by local afar pastoralists, the ingestion of the pod over long periods of time will result in death of cattle. Stomach poisoning by the pod may induce a permanent impairment of the ability to digest cellulose. This might be due to the high sugar content of the pod that depresses the rumen bacterial cellulose activity, and finally kills the animal,” they said.
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