– Clif Little, OSU Extension Guernsey County
Beautiful small yellow flowers blanket the pasture in this picture. Blooming throughout the summer and gradually occupying most of this field is a perennial poisonous plant called Tall Buttercup. This plant starts blooming in June and produces many typically bright yellow flowers of 5 or more petals with flowers spreading 3/4 to an inch in width. The leaves are lobed 3 segments at the base of the plant and become more deeply lobed and segmented further up the plant. This forb can grow up to 3 ft. high. Animals avoid eating this plant allowing it to mature and reproduce. It produces numerous 1/8 inch, flattened kidney shaped seeds organized in small circular clusters. Tall buttercup is very aggressive in unmanaged meadows and pastures and quickly overtakes the field.
Tall Buttercup contains bitter, irritating oil called protoanemonin that is poisonous to livestock. The toxicity is reported to vary depending on plant age, growing conditions and freshness of the forage. The oil in fresh plant stem causes irritation and blistering of the skin, lining of the mouth and digestive tract. Thankfully tall buttercup does not taste good so animals avoid it if desirable pasture plants are present. The toxic oil evaporates quickly, so hay containing buttercup is not toxic.
In many states tall buttercup is considered a noxious weed. The OSU Weed Control Guide, Bulletin 789, available from your local OSU Extension office list several herbicide options for buttercup. Before purchasing an herbicide be sure and review the entire product label for all restrictions unique to your forage management.
EDITOR’s NOTE: For more on pasture and hay field weeds and their proper identification, see this 15 minute presentation from Mark Landefeld.