Also called common dog fennel and stinking chamomile, mayweed is an annual belonging the the aster family, Asteraceae, that also includes daisy, yarrow and lettuce. It is native to Eurasia but was introduced into North America where it is found in disturbed areas such as fields, meadows, and gardens all across the US. Although plants prefer a sunny site with well drained soil, they can grow in clay soil. An attractive plant, it can be distinguished from true camomile by the unpleasant odor produced by the leaves when crushed.
Description: Growing 12-18″ tall, mayweed has a short, thick taproot and upright branched stems that carry hairy, finely divided, fern-like leaves that resemble those of common yarrow (Achillea millefolium). From summer into fall, small daisy-like flower heads appear that are one inch across and have yellow white ray flowers surrounding a center of yellow disc flowers. The fruits are wrinkled, ribbed achenes.
Control: Because plants are annual that spread by seed, removing them before seed set is essential. Mulch to prevent seeds from sprouting; pull or hoe seedlings; pull, cut, or pow larger plants before they produce seed.