Synonym: Ranunculus delphinifolius
Yellow water-buttercup from along the Central Patrol Road, Malheur National Wildlife Refuge.......June 26, 2000.
Yellow water-buttercup is an aquatic perennial with freely branching, hollow stems. Some plants may be entirely free-floating with only tips of the leaves and stem and flowers emergent from the water, while others may be totally exposed and out of the water. On mud flats , its stems are lax to prostrate and its stems root easily at the nodes. The leaves are all found alternating along the stems, with two types of leaves. Those of the lower stems have petioles several times longer than the blades which are 2-8 cm long and 3-5 times ternately dissected into many needle-like segments while the upper leaves are dissected into thicker, branching linear segments (See photo at right.)
The flowers are typically elevated above the water's surface. The 5 greenish-yellow sepals are spreading and quickly deciduous, measuring from 5-8 mm long. The 5 (sometimes 6-8) yellow petals are 9-12 mm long The stamens number 50-70.
Yellow water-buttercup is found in shallow ponds, marshes, slow moving streams or rivers, and on mud flats at lower elevations.
Yellow water-buttercup may be found to the east of the Cascade Mountains from southern British Columbia to northern California and east to Ontario and south through the Mississippi Valley to Louisiana. It is also found in the Mid Atlantic states but is absent in the Rocky Mts.
In the Columbia River Gorge it may be found between the elevations of 400'-700' on the Major Creek Plateau.