The receptacular chaff is usually quite visible as the slender bristle-like tips extend well up among or beyond the tips of the mature disk flowers.

1. Receptacle completely chaffy (all the way to the marginal disk flowers); ray flowers pistillate; involucre ca. (4-) 4.5-6 (-6.5) mm long; achenes ribbed but otherwise smooth; plant nearly or quite odorless.

A. arvensis

1. Receptacle not chaffy around the marginal flowers of the disk; ray flowers sterile; involucre ca. 3-4.2 mm long; achenes warty-tuberculate; plant with unpleasant odor.

A. cotula