Other common names are Pennsylvania knotweed, Pennsylvania smartweed, pinweed, purple-head
Life cycle: summer annual
Growth habit: prostrate; grows from 1 to 4 ft. tall; leaves alternate, lanceolate, smooth margins, sometimes with a purplish thumbprint marking the 2 to 3 in. leaf; conspicuous ocrea surrounding point where petiole meets stem
Reproduction: seeds from pink flowers in the spike-like clusters; can become almost invasive if allowed to go to seed
Conditions that favor growth: common weed of nursery crops and landscapes; rarely a problem in turfgrass; tolerates a range of soil types and conditions
Cultural control: Remove young plants before flowers form
Still have a question? Contact us at Ask Extension.