河岸边的日本虎杖蔓延得很快，很难彻底清除。

The ___knotweed along the riverbank spreads quickly and is hard to eradicate completely.

花园角落里长着一丛丛蓼科杂草，需要尽快清除。

Clumps of ___knotweed are growing in the garden corner and need to be removed soon.