Lafleya, Larfleya, Rarfureruyuayuryu... whatever. Ultraman Nexus has never gotten a translation (like most ultraman series), so this thing has no official spelling for its name. It is nominally based on the Rafflesia flower, but it's probably Lafleya, not Raffleya. Ah, well.
Like most evil plant monsters, it showers poison everywhere. Unlike most, it's a flower the size of a city block.