Clump forming perennial
Herbaceous invasive; leaves deeply dissected, similar to ragweed, but strongly scented like chrysanthemum; Height to 4 ft., but tolerates close mowing and cultivation. Very difficult to control.
Spreads by extensive rhizomes; flowers inconspicuous in terminal leafy spikes
Never till it. Each root piece will generate a new plant. You can smother it (black plastic or layers of newspapers covered with mulch). Or you can exhaust the root system by continuous pulling or removal of the leaves (this is difficult.) You can also use a systemic non-selective herbicide that contains glyphosate that will travel down and kill the roots. Be careful to protect non-target plants from the herbicide. A combination of these methods is the best approach.