Roughseed buttercup  (Ranunculus muricatus)

Roughseed buttercup is also called rough-fruited buttercup. In California, it is a winter or summer annual or biennial. It inhabits regions up to 2300 feet (700 m) above sea level in the Central Valley and San Francisco Bay regions. Like all buttercups, roughseed buttercup can cause toxicity to livestock. The toxic compound, ranunculin, degrades in hay when dried.

Habitat

Moist or seasonally wet places including agronomic fields, marsh margins, stream banks, turf, grasslands, meadows, roadsides, and ditches.

Seedling

Cotyledons (seed leaves) are oblong and hairless. The next young leaves have three lobes, are as long as the seed leaves, and are hairless. Stalks of the leaves are as long or longer than the leaf blades. Leaves alternate on the stem.

Mature plant

Grows erect or along the ground up to 1.5 feet (0.5 m) long.  Leaves are simple, semi-circular to kidney-shaped, hairless, or have few hairs.  Lowest leaves are lobed typically halfway to the base. Upper leaves often have shallower lobes and are slightly smaller than the lower leaves. Lobes are toothed. Leaves alternate and lack stipules (very small leaves) at the base of the stalks.

Flowers

Flowers from March to June. They grow singly and are bright yellow with 5 petals and 10 stamens. Flower stalks are 0.4 to 2 inches (1 to 5 cm) long.

Fruits

Fruiting heads are nearly spherical and produce 10 to 20 single-seeded achenes, per cluster. Achenes are flat, 0.25 inch (6 mm) long, hairy, have spines covering the sides with a curved beak at one end.

Reproduction

Reproduces by seed.

Related species/Similar looking plants

• Many buttercups look alike
• Spearwort
• Creeping buttercup

More information

Broadleaf ID illustration
Calflora's distribution map