Vernal Pool Buttercup

Common name: Vernal Pool Buttercup

Scientific name: Ranunculus bonariensis var. trisepalus
Family: Ranunculaceae (buttercup)
Habitat: vernal pools
Size: plant 2 to 8 inches tall; leaves 6 to 20 mm long; flower 6 to 10 mm across

Fun facts: Vernal Pool Buttercup shades out other plants with its floating leaves.

Description: Member of the buttercup family. The small flowers have tiny yellow petals. The head of seeds is much larger than the flower was and resembles an unripe berry.

Two other buttercups occur at Mather Field. One has large, maple-shaped leaves, yellow flowers and seeds that are covered in hooked spines. The other is white-flowered with fern-like leaves and grows in the water.

Life cycle: Vernal Pool Buttercup is an annual. It germinates in wet areas soon after the rains begin in the fall. It has two forms, one suitable for wet vernal pools and one for dried vernal pools. Its early leaves have long stems so that they can float on the surface of the water. Leaves produced after the water begins to evaporate have shorter stems. Vernal Pool Buttercup blooms in April.

Ecology: Vernal Pool Buttercup is usually one of the dominant species in the pools in which it occurs. It grows very fast and produces leaves which float and shade the bottom of the pool. Fast growth helps it to compete well against other plants. The shading leaves reduce the competition from other species buy preventing sunlight from reaching their seedlings.