The enormous bed of flora, drifting on the waters flowing from northern Thailand towards the sea, is a nightmare for the government during its annual struggle to prevent the water hyacinth from bringing the country’s rivers and canals to a standstill.
The rainy season between July and October also brings in its wake hundreds of thousands of tons of water hyacinth, or Eichhornia crassipes, that threatens to clog up the vast network of waterways across the country – its lifeline for goods transportation as well as agriculture.
Earlier this month, Prime Minister General Prayut Chan-ocha even issued a directive to mobilize army personnel to fight the water hyacinth menace.
Two weeks ago, aided by heavy machinery and local authorities, a detachment of soldiers managed to clear away nearly 120,000 tons of this floating plant from the central province of Ayutthaya.
But days later, a fresh, three-kilometer-long green carpet was on its way to the same region.
The problem is not new for Thai authorities, who have been fighting the quiet invasion of “phak tob java” – as the plant is locally called – for over a century now.
Botany books say the species was introduced into Thailand at the dawn of the 20th century by a member of the royal household who chanced upon the plant during a visit to Indonesia.
Initially used to adorn gardens and royal palaces due its eye-catching mauve flowers, the hyacinth managed to gain a foothold in the wild as it began its invasion.
The International Union for Conservation of Nature has termed water hyacinth – native to the Amazon basin but now found in places as diverse as Florida mangroves or Africa’s Lake Victoria – as one of the 100 most dangerous invasive plant species worldwide.
In tandem with other aquatic plants, it can form a dense layer, block out the sun’s rays and wipe out native flora below.
Heavy presence of the hyacinth also reduces oxygen in the water, killing marine fauna.
Although authorities under King Vajiravudh brought in laws in 1913 to curb cultivation of this plant, and spearheaded an eradication campaign, it is yet to bear fruit.
Talking to the Bangkok Post newspaper, Rangsit University professor and biologist Duangporn Suwanagul underlined the weed’s ability to adapt to different environmental conditions, and opined that “authorities can do a good job cleaning up. But after a few weeks, the weed will return again. What they needs is a long-term strategy to control and manage it.”
In 2015, Kasetsart University molecular genetics researcher Jureerat Leesmidt was awarded for discovering how to produce cooking gas using water hyacinth.
In a telephone conversation with EFE, the researcher spoke about the new developments in finding productive uses for the weed, including as organic fertilizer, cattle feed and a natural filter against toxic substances.
“The weed per se is not a bad guy, but it grows very fast. The problem appears when the rate of growth exceeds that of consumption” of resources derived from it, she explained.