1. a plant with jointed stems and small flowers, often considered a weed

Examples

• Japanese knotweed is an invasive species that spreads rapidly.
• The gardener struggled to remove the knotweed from her flower bed.
• Knotweed can grow through concrete and damage building foundations.
• The riverbank was covered with dense patches of knotweed.
• Some species of knotweed are used in traditional medicine.
• The city hired contractors to control the knotweed infestation.