White water buttercup is an aquatic, perennial wildflower with lax, submerged stems measuring from 10-100 cm long. The herbage is somewhat glabrous to pubescent and the lower nodes of the stem are known to root upon touching bottom. The leaves alternate along the stems, the submerge leaves dissected into many needle-like segments. The lower leaves are typically sessile while the upper leaves may have petioles measuring up to 2 cm long. The floating leaves are similar to the lower leaves but are 5-15 mm long and nearly twice as wide, the blades blades shallowly to deeply 3-lobed and with toothed or lobed segments.
The 5 greenish sepals measure from 2-5 mm long and are soon deciduous. The 5 white petals (sometimes yellowish toward their bases) measure from 5-10 mm long. The stamens number from 10-15.
Leafy Water Buttercup: var. aquatilis (Synonyms: Ranunculus aquatilis var. hispidulus, Ranunculus trichophyllus var. hispidulus) - Floating leaves broader, three-lobed than the linear or filiform, submerged leaves.
White Water Buttercup: var. diffusus (Synonyms: Ranunculus aquatilis var. caespitosus, Ranunculus aquatilis var. capillaceus, Ranunclus aquatilis var. porteri, Ranunculus aquatilis var. subrigidus, Ranunculus aquatilis var. trichophyllus, Ranunculus longirostris, Ranunculus subrigidus, Ranunculus trichophyllus, Ranunculus trichophyllus var. trichophyllus) - Floating and submerged leaves similar, linear to filiform in outline.
White water buttercup is found in slow moving streams, ditches, or ponds and occasionally on mud.
White water buttercup may be found in moist habitats throughout much of North America and Europe.
White water buttercup in a pond at the Dalles Mt. Ranch in the Columbia Hills State Park in south-central Washington..........June 8, 2008.