Buttercup family (Ranunculaceae)
Description: This herbaceous perennial plant is up to 1½' tall. It forms a rosette of leaves, from which flowering stems develop. The basal leaves are up to 3" long and 1½" across. They are usually trifoliate, although some basal leaves may be deeply 3-lobed and simple. The terminal leaflet usually has a short stalk, while the side leaflets are sessile. Their margins are often cleft or coarsely dentate. Each basal leaf has a long hairy petiole, and its upper surface often has pale white blotches. The alternate leaves of the flowering stems are smaller in size, usually ovate and shallowly lobed. They have short petioles. Both types of leaves are usually pubescent or hairy.
Each flowering stem is hairy and produces only a single or a few flowers at its apex. A flower is about ¾" across and consists of 5 bright yellow petals. These petals are well-rounded, quite shiny, and overlap each other. Toward the center of the flower, there are numerous stamens with yellow anthers surrounding the ovaries. There are 5 hairy green sepals that are lanceolate and spreading (not sharply recurved). They are much shorter than the petals. The blooming period occurs from late spring to mid-summer, and lasts about 1-2 months. The flowers are often fragrant. The ovaries in the center of the flower are replaced by a small cluster of achenes. These achenes are flat-sided and have a short stout beak. The root system is fibrous and produces stolons up to 2' long that can root at the nodes. As a result, this species often forms vegetative colonies.
Cultivation: The preference is full or partial sun, moist conditions, and fertile loamy soil. This plant can spread aggressively in areas that are at least partially sunny and moist. It can withstand regular mowing in lawns.
Range & Habitat: Creeping Buttercup has naturalized in many counties of NE Illinois and a few counties elsewhere (see Distribution Map). It is occasionally grown in flower gardens and lawns because of the attractive flowers, otherwise it is uncommon. Habitats include lawns, gardens, moist disturbed meadows, ditches, and areas along roadsides. This species was introduced into North America from Europe, and all populations in the wild have escaped cultivation. It appears to have the potential to invade some natural habitats, but so far it has not been a serious problem in Illinois.
Faunal Associations: The nectar and pollen of the flowers attract short-tongued bees and flower flies primarily. Other visitors include long-tongued bees and beetles. The latter feeds on the pollen (or the flowers) and is less effective at pollination than the bees. The seeds are occasionally eaten by birds in limited amounts, while the foliage is usually avoided by mammalian herbivores because it contains a blistering agent that can irritate the gastrointestinal tract.
Photographic Location: A front lawn in Urbana, Illinois.
Comments: Creeping Buttercup can produce bright yellow flowers in lawns during the early summer after the spring-blooming flowers, such as Claytonia virginica (Spring Beauty), have finished blooming for the year. However, it has the potential to escape into natural areas where it may displace native plants. There is a double form of Creeping Buttercup that has 10-20 petals per flower, rather than the usual 5. It also escapes into the wild, but is less common. Creeping Buttercup can be distinguished from other Ranunculus spp. by the presence of its stolons and the pale white blotches on the leaves. Other distinguishing features include the spreading hairy sepals (shorter than the petals and not sharply recurved) and the shape of the leaves.