PROSTRATE KNOTWEED AND ERECT KNOTWEED
GROWTH HABIT: Extremely variable annuals with wiy stems. Nodes are somewhat swollen, often surrounded with the torn remnant of a short, papery leaf sheath.
LEAVES: Leaves are generally lance-shaped, blue-green and alternate. Inconspicuous, greenish- white flowers are borne in the leaf axils.
OTHER: Several species occur in our region, including prostrate and erect knotweed. P. aviculare L. basal branches become prostrate, while P. erectum L. is more upright. Knotweed is a native of the Old World, but is now distributed throughout North America. It can become a problem in irrigate and dryland crops, as well as in waste areas and other non-crop sites. Prostrate knotweed seems to thrive in dry compacted soils.