Dear Friends of Maine Lakes, Thank you for visiting our Interactive Field Guide! Though the primary content pertaining to species identification in this Guide is—for the most part—still correct and useful, the site itself is no longer fully-functional (nor able to be updated). The entire Guide will soon be replaced by a new, expanded website-version of the Maine Field Guide to Aquatic Phenomena. So please stay tuned! Thank you for your patience!

Go to VLMP Home Page


Ranunculus aquatilis var. diffusus and Ranunculus flabellaris

NOTE: Worldwide, most botanists classify the two species described here as being in the genus Batrachium. The genus classification of Ranunculus for these two species is confined primarily to the United States, and is the exception.

Water crowfoot stem
White water crofoot specimen

Habitat: Sixteen different Ranunculus species occur in Maine. Several of these are aquatic species, and two: white water crowfoot (Ranunculus aquatilis var. diffusus) and yellow water crowfoot (Ranunculus flabellaris), are possible invasive aquatic plant look alikes. Both water crowfoot species grow in the submerged plant community, generally in quiet to slow moving water up to two meters in depth. Yellow water crowfoot is well adapted to life at the water's edge and is often found in its terrestrial form, stranded along muddy shores. In Maine, white water crowfoot is more common than yellow water crowfoot.

white water crowfoot flower
White water crowfoot in flower

Description: The leaves of both water crowfoot species are borne on long, branching stems emerging from trailing runners or buried rhizomes. Both species have small (1 to 2 cm long) branch-divided leaves, arranged alternately along the stem. The leaves of white water crowfoot are finer, more delicate, and thread-like (round in cross-section). Like the leaves of many aquatic plants, they go limp when removed from the water. The leaves have slender petioles that widen at the stem to form a clasping sheath that wraps all the way around the stem. The leaves of yellow water crowfoot are courser, flattened, and hold their shape when removed from the water. Distinct leaf stems may be absent. Both species produce small buttercup-like flowers, with five petals. The flowers of white water crowfoot are white; the flowers of yellow water crowfoot are yellow. Tiny beaked fruits or nutlets form in clusters on slender stalks.

Yellow water crowfoot flower
Yellow water crowfoot in flower

U.S. Range: Both water crowfoots are native to Maine, New England and much of the United States. In Maine, white water crowfoot is more common than yellow water crowfoot.

Annual Cycle: Water crowfoots are aquatic perennials, dying back to their rhizomes as winter sets in, and overwintering in the sediments. New growth emerges as the water warms in the spring. Flowers are produced in the early summer, followed by fruits in mid-summer. Plants propagate from seed, and also reproduce vegetatively from stem fragments, rhizomes and runners.

Value to the Aquatic Community: The fruit and foliage of water crowfoot is a source of food for some waterfowl; the plants also offer food and shelter for fish.

Look Alikes: May be confused with other plants with finely divided leaves including bladderworts, fanwort, hornwort species, mermaid weeds, water marigold, and leafy water-milfoils.

Print out a copy for the field
(Adobe Acrobat file) - To get the free Acrobat Reader go to


Click Images for Larger Version
white Water crowfoot flower white Water crowfoot stem yellow Water crowfoot flower yellow Water crowfoot stem white Water crowfoot fruit illustration white Water crowfoot illustration yellow Water crowfoot illustration

Secchi Disk
Water Quality Monitoring
Invasive Target
Aquatic Invasive Monitoring

Maine Volunteer Lake Monitoring Program
24 Maple Hill Road, Auburn, ME 04210

2009 Maine Volunteer Lake Monitoring Program | website comments to:

bottom wave