Distribution: An introduced, ubiquitous weed, found throughout the United States.
Habitat: Dry or slightly moist, disturbed soil, often where hard-packed.
Origin: Both native and introduced
Flowers: July - September
Growth Duration: Annual
– common knotweed, yard knotweed
– American knotweed, prairie knotweed
– common knotweed, oval-leaf knotweed
– narrow-leaf knotweed