Ranunculus aquatilis L.

White Water Crowfoot

© SRTurner

Family - Ranunculaceae

Habit - Perennial forb, usually growing in water.

	Population of plants in a small pond.
© SRTurner

Stems - Weak, prostrate or matted, or floating in water, mostly 30-80 cm long, usually rooting at the lower nodes, glabrous or nearly so, without bulbils, the base not bulbous-thickened.

	Stem and leaves.
© SRTurner

Leaves - Alternate, dissected. Basal leaves absent at flowering. Stem leaves short-to moderately petiolate, the petioles usually appearing somewhat thickened or inflated, the blade 0.6-4.0 cm long, 1.5-5.0 cm wide, broadly fan-shaped to semicircular or kidney-shaped in outline, 2-4 times ternately then dichotomously dissected into linear or threadlike, sharply pointed segments, the base broadly angled to truncate or cordate, the margins otherwise entire.

	Leaf.
© SRTurner

	Leaf.
© SRTurner

Flowers - Sepals 5, 2-4 mm long, spreading or reflexed from the base with age (lacking a transverse fold or joint), plane. Petals 5, 4-10 mm long, 4-7 mm wide, obovate, noticeably longer than the sepals, white, occasionally yellow toward the base. Style present.

	Flower.
© SRTurner

	Flower.
© SRTurner

	Sepals.
© SRTurner

	Stamens.
© SRTurner

Fruits - Head of achenes 2-4 mm long at maturity, hemispheric to more or less globose, the receptacle hairy or rarely glabrous. Achenes 1.0-1.8 mm long, the dorsal margin keeled but usually unwinged, the wall thick, with coarse transverse ridges, glabrous or hairy, the beak 0.2-1.2 mm long, slender or threadlike, straight or curved.

Flowering - May - July.

Habitat - Submerged aquatics in streams, rivers, spring branches, ponds, lakes, sloughs, swamps, and oxbows; uncommonly terrestrial when stranded in mud along receding shorelines.

Origin - Native to the U.S.

Lookalikes - Cabomba caroliniana.

Other info. - This unusual species of crowfoot is found in Missouri mostly in a cluster of counties in the south-central part of the state. It occurs as R. longistyris, in somewhat scattered fashion, throughout much of the U.S. It is easily recognized by its aquatic habitat and five-petaled white flowers which poke above the surface of the water. It can be distinguished from Cabomba caroliniana in having numerous stamens and alternate leaves. In Cabomba caroliniana, flowers have six stamens and the leaves are opposite.

Another name for the species is Ranunculus longirostris, although some botanists have considered these as different species. Differention has relied on characters which show continuous gradation and probably represent phenotypic variation.

This species is unusual in lacking the toxicity typical of Ranunculus.

Photographs taken near Hyannis, Grant County, NE, 5-9-2025 (SRTurner).