Image of various buttercup facts

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Bur buttercup (Ranunculus testiculatus)

Along with yellow and desert alyssum, bur buttercup is one of the first weeds to flower in the spring. It is a non-native annual that often forms a carpet of yellow along roadways, parking lots, and other disturbed areas. Flowers, which have 2-5 yellow petals, last about 3-4 weeks and then form bur-like seed heads. These burs can cling to animal fur or human clothing, and they become very prickly as they dry. Other common names for bur buttercup are hornseed buttercup or curveseed buttercup, both describing the plant’s bur-like anatomy. This species is a “dwarf” plant, growing only 1-3 inches tall. It has basal leaves that are <1 -4 inches wide, and leaves are divided into 3 ovate, lobed leaflets. Leaf shape can vary. Leaves and stems are pale green and have short, woolly hairs. Although this species is often overlooked, it can be an agricultural pest and toxic to livestock. It typically grows in areas where little to no other vegetation is growing. Bur buttercup can be managed with an appropriate herbicide in bare ground environments, but remember that it flowers very early in the spring. In other areas, limiting disturbance and nurturing the growth of other vegetation is recommended. 

Not to be confused with

Image of two kinds of buttercup

There are over 30 buttercup (Ranunculus) species in Montana. Sagebrush buttercup (Ranunculus glaberrimus) is native and one of the first wildflowers to bloom, dotting the drab-colored rangeland with a dash of yellow. This species is usually found in dry, open valleys and foothills.

Tall buttercup (Ranunculus acris) is a priority 2A noxious weed in Montana that typically grows in moist fields or wet meadows. It grows up to 30” tall and flowers in late May to June.