This is a blood-sucking plant that grows wild on the fictional Donburako Island. Donburako is a Japanese onomatopoeia (it sounds a bit frumpy, though) used to express the state of something (often quite big, probably) flowing its way while floating on water.
At his request, Booska, Chamegon and their friends helped him to search the island that kept drifting in the ocean as it was composed of pumice, and they managed to get there.
The treasure was sucked and swallowed by the blood-sucking plant 300 years ago, and people were changed into cacti with white powder its flower sprayed over them.
When the plant went at Booska, it wrung him with its vines and troubled him a lot showing its intimidating power, but Booska got to defeat it finally after fighting against the mysterious monster courageously.
It might be the first time that I have seen Booska battle with an enemy so seriously, which tells the blood-sucking plant was such a formidable creature.
When beaten by Booska, it vomited the treasure it had swallowed 300 years ago, which made Captain Donkey so happy, and the people changed into cacti returned to humans.
Along with this allegedly blood-sucking plant, another species was found on this island that wound up Chamegon although it was beaten by Chamegon with his ring-like ray fired from his tail.