By PR Extension Office

Seemingly unaffected by drought, bur buttercup is growing and blooming. This small yellow flowering annual is one of the earliest weeds to appear in the spring according to Powder River Extension Agent Mary Rumph. It is a winter annual that emerges, flowers and sets fruit when the temperatures climb into the 45-50 degree range. Plants only grow to be 2 or 3 inches tall. They often occur in dense mats which cover large areas of the ground.

Each blossom usually has 5 bright yellow petals. The flowers are tiny, measuring less than a quarter inch long. At maturity, each blossom develops into a bur, which dries and turns brown.

This plant contains ranunculin, which changes into a highly toxic compound, protoanemonin, when the plant is crushed. Sheep have been poisoned and have died in the western United States after ingesting aboveground plant material. This plant is considered highly toxic. Signs of poisoning include anorexia, labored breathing, diarrhea, dyspnea, recumbency, weakness, and death.

It is a small, gray-green tap rooted plant with three to four deeply lobed, fine-haired leaves resembling antlers. By early summer, it scatters its seed and its burs have turned from green to straw-colored to brown. The burs, though not as sharp as puncturevine seeds, are painful if stepped on with bare feet.

Bur Buttercup primarily grows in waste areas. It is best controlled before it produces flowers and seeds. Hoeing, pulling and digging can control it; it can also be sprayed (depending on its location) with 2,4-D, Ally, Banvel, or Roundup. Contact the Powder River Extension Office at 436-2424 or Rumph at [email protected] for more information.