In Ky. this weedy winter-annual of southeastern states has sometimes been confused with procumbens, especially in early records (e.g. Gm). C. tainturieri differs from procumbens as follows (W): ribs of fruit broad (versus narrow), the intervals between the ribs much narrower than the ribs (versus equal or wider); pedicels somewhat club-shaped (versus mostly uniform); stem and leaf surfaces mostly pilose (versus essentially glabrous). Hybrids have not been reported anywhere. The first reliable records of tainturiei were not until the 1930s (Greenwell 1935; B), and it may have spread north into Ky. after settlement. It generally occurs in more open habitats than procumbens, and it is often associated with roadsides.