Knawel is a winter annual which, when it first germinates, may go unnoticed because of its grasslike features. It closely resembles parsley-piert and lawn burrweed. It is a freely branched plant with spreading stems. Leaves, clasping the stem, are opposite, linear, less than 1 mm wide, and sharp-pointed. The very inconspicuous flowers are clustered in the leaf axils. They are small, green, lacking petals, and somewhat spiny to the touch.
Winter annual broadleaf weeds germinate in the fall or winter and grow during any warm weather, which may occur in the winter, but otherwise remain somewhat dormant during the winter. They resume growth and produce seed in the spring and die as temperatures increase in late spring and early summer. They quickly invade thin turf areas especially where there is good soil moisture. Shade may also encourage growth. Many have a prostrate growth habit and are not affected by mowing. A dense, vigorous turf is the best way to reduce the encroachment of winter annual weeds. First, select adapted turfgrass cultivars for your area and then properly fertilize, mow, and water to encourage dense growth.
Growth Season/Life Cycle
winter annual weed
prostrate, spreading; can form low mats or clumps in established turfgrass
four or more
very inconspicuous green flowers