The alien creeper is sweeping across Nepal from east to west and has devastated trees in the Chitwan National Park (CNP), threating more than half the park's vegetation.

Known as "lahare banmara" by locals, the weed has the Latin name Mikania micrantha, and has covered nearly a quarter of the national park in Chitwan. Mikania is like the previous banmara weed which is a native plant in Mexico and arrived with American wheat aid in the 1960s.

The super weed, native to south and central America was introduced to India during world War II to camouflage army camps. It was first reported in Nepal in 1965 in Ilam where it probably came through tree saplings imported from northeast India.

"But it is in the past few years that it has suddenly gone virulent and already has spread as far west as Dang," explains Naresh Subedi at the National Trust for Nature Conservation, who is also doing a PhD on how invasive plant species are affecting rhinoceros.

Chanda Rana of the group, Save the Environment, is also concerned about the weed affecting the rhinoceros habitat. "Mikania needs open space and grasslands next to river banks which is where rhinoceros graze," she says. The weed destroys a plant that is called "rhino's apple" because the animals love the fruit." Before rhinos, the weed also affected the wild buffalo herds in Kosi Tappu by smothering the buffalo's preferred plants.

Chief Warden Jhamak Karki of Chitwan says the weed is now a serious enough threat for the park to go on a war footing. Mikania is prolific because it produces as many as 40,000 viable seeds every year per plant which is dispersed by the wind. The weed can also propagate itself with a broken stem. Livestock refuse to eat the weed and the only use for it is to use as fuel. Herbicides are not recommended because of the toxic effect on the environment.

While research into fighting this menace continues, Rana says: "The only way we have seen so far to fight the weed is to physically uproot every plant, but this is time consuming and difficult."

Stuti Sharma

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