Ranunculus sceleratus L.

Cursed Crowfoot

© SRTurner

Family - Ranunculaceae

Habit - Annual forb with usually exensive, fibrous, somewhat fleshy roots. Terrestrial or emergent aquatic.

Stems - Ascending to erect, to 60 cm, stout but hollow and easily broken, glabrous, branching, the base not bulbous.

	Stem and node.
© SRTurner

Leaves - Basal and alternate. Basal leaves present at flowering, long-petiolate, the blade 1-7 cm long, 3-9 cm wide, kidney-shaped to more or less semicircular, deeply 3-lobed, the base broadly cordate or less commonly truncate, the lobes obovate to bluntly rhombic, at least the central lobe usually again 3-lobed, rounded or bluntly pointed at the tip, the margins otherwise scalloped. Stem leaves mostly short-petiolate to sessile, deeply 3-lobed or-parted nearly to the base, the lobes linear to oblanceolate or narrowly rhombic-elliptic, the margins entire or nearly so or those of the lower leaves shallowly lobed or bluntly toothed or scalloped.

	Basal leaves.
© SRTurner

	Basal leaf blade, abaxial.
© SRTurner

	Stem leaf.
© SRTurner

	Lower leaf.
© DETenaglia

	Upper leaves.
© DETenaglia

Inflorescence - Flowers on short or long peduncles terminating branches, often appearing axillary. Peduncles glabrous or with few sparse hairs, subtended by leafy bracts.

	Inflorescence.
© SRTurner

	Inflorescence.
© SRTurner

Flowers - Sepals 3-5, 2-4 mm long, reflexed from at or just above the base (lacking a transverse fold), more or less plane. Petals usually 5, free, 2-5 mm long, 1-3 mm wide, obovate, as long as or slightly longer than the sepals, glossy yellow. Style absent. Stamens about 20, from base of pistils. Filaments to 2 mm long, glabrous, pale yellow. Anthers yellow, 0.3 mm long. Pistils in a cylindric head expanding in fruit.

	Flower.
© SRTurner

	Flower.
© SRTurner

Fruits - Head of achenes 3-12 mm long at maturity, at first globose to ovoid but usually becoming cylindric, the receptacle sparsely hairy or glabrous. Achenes 0.8-1.2 mm long, flattened, the margins corky-thickened, unwinged, the wall thick, with a network of very fine cross-wrinkles, glabrous, the beak essentially absent (reduced to a minute, off-center, peglike structure).

	Fruit cluster.
© SRTurner

Flowering - April - August.

Habitat - Streambanks, pond margins, sloughs, swamps, marshes, crop fields, pastures, ditches, muddy disturbed areas.

Origin - Native to the U.S.

Lookalikes - R. abortivus, R. flabellaris.

Other info. - This plant is found in scattered locations in Missouri, most common by far in counties bordering the large rivers. It is likewise widely scattered across the eastern half of the U.S., and in west coast states where it is apparently introduced. Identification is straightforward, with the plant having all basal leaf blades lobed, fleshy stems, and small buttercup-pattern flowers. The petals are glossy, as is the case with most buttercups. The petals are also rounded at the apex, which serves as a quick means of distinguishing this species from R. abortivus (check the basal leaves for confirmation). The plant is often found in fallow crop fields located in large river floodplains.

R. sceleratus is one of the most toxic of the buttercups, most of which are poisonous to some degree due to their content of the compound protoanemonin. The plant has been documented to poison cattle, or in lesser amounts to impart a bitter flavor to their milk. The sap can cause serious dermatitis and blistering in susceptible individuals. The specific epithet sceleratus means "acrid" or "blister-drawing," and the common "cursed" moniker probably also references this property. Missouri plants belong to var. sceleratus. Another variety, var. multifidus, occurs in the western half of the continental U.S. It is characterized by more deeply and regularly divided leaf blades, and achenes with the lateral faces smooth except for a ring of minute pits.

Photographs taken in Parkville City Park, Parkville, MO., 6-10-00 (DETenaglia); also at Klondike County Park, St. Charles County, MO, 5-15-2014, near Labadie, Franklin County, MO, 5-17-2019, Pacific Palisades Conservation Area, MO, 5-18-2019, and the Katy Trail near Dutzow, Warren County, MO, 4-3-2020 (SRTurner).