What's that yellow flower blooming in fields around Ada?

Cressleaf groundsel, also called butterweed, is a yellow flower in bloom this month in rural Ada area and across Ohio. This field is north of Ada. It is an increasing concern for many livestock producers as it is toxic to livestock. Cressleaf reproduces from seeds and emerges as a rosette in the fall, then bolts, flowers, and goes to seed in the spring.  Plants eventually produce seeds resembling those of dandelions. Click here for more details from Mark Badertscher, county extension office.