Spread of Manjakonna has risen by 10% from 2015, says KFRI survey

After posing a serious threat to the flora and fauna in the forest areas of the Nilgiri Biosphere Reserve, including Wayanad Wildlife Sanctuary (WWS), Senna spectabilis (Manjakonna in local parlance), an alien invasive plant, has started to flourish in forest and non-forest areas of the State.

A recent survey of the Kerala Forest Research Institute (KFRI) reveals that the plant has started to invade various parts of Palakkad district, including Attappady, Anakkatti, Kottathara, and Sholayar regions.

“The spread of the exotic plant has increased more than 10% from 2015. This shows its high invasive nature,” says T.K. Hrideek, scientist, KFRI.

The wild growth of the plant is high in Tholpetty, Sulthan Bathery and Muthanga forest ranges of the WWS, Dr. Hrideek, who is coordinating the survey, said.

Plantations hit

Recently it started to spread to plantations also, Dr. Hrideek said. Earlier, it was planted as avenue trees along roadsides in Wayanad. Due to massive flowering and drying of bamboo species in the Wayanad, lots of open spaces were created which were occupied by Senna spectabilis.

The ‘vayal’ ecosystem (marshy land) of the forest area now houses this plant in large numbers. The allelochemicals produced by this plant adversely affect the germination and growth of the native species, K. Murali Krishnan, a member of the team said.

This plant is also seen in Kannur, Kozhikode, Thiruvananthapuram, and Idukki districts.

While the plant is growing in the garden of Napier Museum in Thiruvananthapuram, it is grown as an avenue tree in recently constructed bypass road and in the garden of railway station in Kozhikode, he added.

Isolated trees are also seen in teak plantations of Kannavam in Kannur. But people in Idukki have mistaken it as neem tree, Suby, another member of the team, said.

Invasive nature

The survey shows that this plant shows invasive nature only above 500 m elevation. But in the favourable conditions, it shows invasive nature in lower altitude too. The KFRI is planning to eradicate it by uprooting seedlings and debarking trees.