Native to Europe and western Asia, now widely distributed throughout the United States and into Mexico.
A perennial weed with foliage that dies back in the winter, with regrowth from the roots beginning in late winter to early spring. Propagation also is by seeds that germinate in early spring.
Plants begin to flower in late spring and seeds mature throughout the summer.
Mature plants grow to over 3 feet tall, with large production of white flowers in clusters at the ends of the stems. Multiple branches and stems come from the strong crown of the plant, and it also has an extensive, creeping root system.
Leaves are produced along the stems, and are somewhat thick and leathery. They may have smooth or toothed margins. Lower leaves can be as long as 12 inches, on long stalks. Upper leaves are smaller and either on short stalks or no stalks.
Flowers are in clusters on stalks, and multiple stalks may arise from the end of the stem or from the leaf axils, creating a very large number of flowers.
Characteristicts Important to Control:
This is a perennial with deep rootstocks, making physical removal difficult. It tolerates any soil situation, from moist ditchbanks to dry waste areas to croplands.