This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Native. Annual. Propagates by seeds. Time of bloom: May to August. Seed-time: June to October. Range: New Brunswick to Minnesota, southward to Florida; also in the Rocky Mountains, Colorado, and Utah. Native to Europe and Asia. Habitat: Wet meadows, low pastures, along ditches and in bogs.
Cattle ordinarily are careful to reject all Buttercups, because of their acrid and poisonous juices, but when first turned out to grass in the spring they are likely to graze so eagerly as to get some of the young leaves of this one, which causes an inflammation of mouths and digestive tracts, sometimes so severe as to be fatal. Stem stout, sometimes over an inch thick at the base, smooth, hollow, much-branched, six inches to two feet in height. The alternate leaves are also very smooth and rather thick, the basal ones rounded heart-shape in outline, but deeply three- to five-lobed, bluntly toothed or entire, with long, broad, flattened petioles; stem-leaves also three-parted, but the lobes are more slender, approaching to wedge-shape, those near the top becoming linear. Flowers small, the five pale yellow petals scarcely exceeding the calyx; stamens and styles numerous. Ranunculus fruits are composed of many one-seeded carpels tipped by more or less elongated styles; in this species the heads are oblong, the length nearly thrice the thickness, each one closely set with many minute, short-beaked carpels, each containing one oval, flattened, dull brown seed.
Fig. 104. - Cursed Crowfoot (Ranunculus sceleratus). X 1/4
Cut or pull while in early bloom in order that no seeds shall be allowed to ripen.