Bristly Buttercup is an erect native perennial forb growing on hairy stems from 1.5 to 2.5 feet high. Stem hair is whitish and spreading (bristly). Stems do not root at the nodes, but branch in the upper section.
The leaves are all about the same shape in outline with the lower leaves much larger, stem leaves fewer and smaller. The outline is broadly heart-shaped with 3 stalked divisions or leaflets, each leaflet deeply cleft into what appears to be 3 lobes, each lobe broadly and coarsely toothed. The lower basal stem leaves on long hairy clasping stalks, the upper stem leaves almost stalkless. The leaf surfaces have long whitish hairs.
The inflorescence has a few solitary, or groups of 2 or 3, short-stalked flowers atop the stem branches. Leaves in the inflorescence are stalkless.
The flowers are 5-parted with a hairy receptacle, 5 sepals that reflex fully downward 1 mm above the receptacle base. Sepals are somewhat spatula shape, 3 - 5 by 1.5 - 2 mm, shade in color from yellow at the base to yellow-green at the obtuse tips, hairs on the outside. Sepals fall away after flower pollination. The 5 yellow petals are much shorter than the sepals, more rounded, 2 - 4 by 1 - 2.5 mm. Stamens are numerous and surround a yellow green receptacle of numerous pistils - one per locule, each with a short style. The nectaries are at the base of the petals.
Fruit: Fertilized flowers form a cylindric seed head, 9 to 12 mm high by 5 to 7 mm wide. The head has numerous smooth achenes, up to 2.8 mm wide and 2 mm long, somewhat delta shaped, with a persistent beak from the style, with a narrow rib on the margin, 0.1-0.2 mm wide. Buttercup seeds need some cold stratification for germination, at least 30 days and some species require 60 days.
Toxic: The plant has hazardous elements - see notes below.
Habitat: Bristly Buttercup grows in moist sunny places such as stream banks, shorelines, moist clear area. The roots are fibrous, not tuberous, the base of the stem not bulbous.
Names: Buttercups comprise about 275 different species. Ranunculus pensylvanicus is in Ranunculus Sect. Ranunculus.The generic name Ranunculus, is from two Latin words, 'rana' meaning ' frog' and 'unculus' meaning 'little' and together they refer to a group of plants, many of which grow in moist places - like little frogs. The species, pensylvanicus refers to the State of Pennsylvania where the first type plant was classified. The family name of Buttercup, used to be "Crowfoot', hence the continuation of the old name in many of the species common names. The author name for the plant classification - ‘L.f.’ refers to Carl Linnaeus the Younger (1741-1783), Swedish naturalist, son of Carl Linnaeus, who did some follow-on work from his father’s work; published Supplementum Plantarum systematis vegetabilium in 1781 and died, childless, of jaundice.
Common Names: Some of the Buttercups have assumed the same common name as others of the genus. R. pensylvanicus is variously listed as Pennsylvania Buttercup and Bristly Buttercup. Bristly Buttercup is also applied to R. hispidus. Best to stick with the scientific name.
Comparisons: Of the other buttercups that grow in moist habitats for comparison - Hooked Crowfoot, R. recurvatus has leaves less deeply cleft and the seed head is not as tall; Cursed Crowfoot, R. sceleratus also has a cylindric seed head, but the leaves are more kidney shaped. Others to look at are:Kidney-leaf Buttercup, R. abortivus; Swamp Buttercup, R. hispidus; Tall Buttercup, R. acris.
Above: The inflorescence is one or several flowers in a cluster atop the stems. Drawing from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.
Below: Two views of the flower head: The longer spatula shaped sepals reflex downward. Flower stalk and sepals are hairy. The 5 smaller yellow petals spread outward. In the center is the receptacle of numerous yellow-green pistils surrounded by a number of yellow stamens.
Below: The long stalked clasping basal leaf.
Below: Detail of the 3-sectioned leaf, each section 3-parted. An outline of the entire leaf would be heart-shaped.
Below: 1st photo - Surface hair on the stem and leaf stalk. 2nd photo - the receptacle after pollination - enlarged with achenes in the green state. Note the beak on each.
Notes: Bristly Buttercup is not believed to have ever been in The Wildflower Garden although it is a fairly common plant in most counties of Minnesota including Hennepin where the Garden is, absent in only a few counties in the southern and western part of the state. In North America it is found in all parts north of line drawn from Oregon to Delaware, including all the lower Canadian Provinces.
Toxicity: Many of the species of Ranunculus are poisonous and will severely irritate the skin. If taken internally the plant can cause stomach inflammation. Cattle can be affected if they eat the plant. When the plant is dried, however, the poisonous material evaporates. Bees have been poisoned when they pick up pollen from Ranunculus species. - see this article on bees - pdf.
Legend: The legend of this plant family is this: Ranunculus, a Libyan boy who sang very beautifully, always wore green and gold silk. While singing in the woods, wood nymphs heard him and to get some peace and quiet, they turned him into a green and gold flower.
Eloise Butler Notes: On April 30, 1911, Eloise Butler published an article in Minneapolis Sunday Tribune in which she discussed Buttercups. Here is what she wrote:
"A number of the early flowering plants are members of the crowfoot family [Ranunculaceae -in current times this family is now called the Buttercup Family], [such] as the anemones and buttercups. In the divided leaves of a crowfoot, as some of the buttercups are called, the early botanists saw a resemblance to a bird’s foot. The buttercups of Minnesota are not so much in evidence as the tall European buttercup [Ranunculus acris L.] the pest of the hay fields - farther east.
One early species, Ranunculus abortivus, [Littleleaf Buttercup] has so small a flower that a novice would scarcely notice it, and is surprised to hear it named a buttercup. Neither would a child be likely to apply the time-worn test of holding the flower to your face to learn if you love butter. This lowly buttercup [her text omits the common name] blooms sparsely on the prairie with the pasque flower. The specific name rhomboideus [prairie buttercup] indicates the shape of the leaf. The low, tufted R. fascicularis [early buttercup] has a larger flower, but is not conspicuously massed. Our two prettiest buttercups are aquatics - one with shining, yellow petals; the other with smaller white flowers and long, railing stems; and both bearing finely dissected leaves.
The large Crowfoot family is without strongly marked characters. Its plants have usually an acrid taste; the leaves are generally more or less cut or divided; the corolla is often wanting, and, when this is the case, the calyx is colored like a corolla; the stamens are numerous; the pistils vary in number from one to several; and all the parts of the flower are distinct or unconnected."
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"