Creeping Buttercup Ranunculus Repens L

PNW 399 • Reprinted January 1996 Creeping Buttercup Ranunculus repens L.

L.C. Burrill

reeping buttercup (Ranunculus repens L.) C probably is the most troublesome of several members of the buttercup family that are weeds in the Pacific Northwest (Figure 1). There are many native species of buttercup in the Pacific Northwest, but the weedy species are of European origin (Figure 2). It’s likely that they were introduced Figure 2.—The size and shape of Figure 3.—Buttercup flowers commonly individual fruits will help you identify have 5 petals but may have up to 10. as ornamentals but escaped to buttercup species. become weeds throughout the United States. Buttercups are found most Most species of buttercup conditions under which the often in lowland pastures and spread by seed, so they con- buttercup grew, and suscepti- in wet areas. They’re most com- tinue to invade new fields and bility of the animal. mon west of the Coast Range, new regions. Movement with Protoanemonin is unstable but a few species are better hay is a common means of dis- and doesn’t retain its toxicity in adapted to conditions east of persal. Creeping buttercup is hay. Stability of the toxin in the Cascades. especially good at crowding high-moisture hay and silage other plants because it also hasn’t been determined. Butter- spreads by creeping stems. cup sap irritates skin and The problem isn’t simply that mucous membranes. buttercups compete with more Cattle usually avoid eating desirable forage plants—they’re buttercup when adequate feed also toxic to livestock. is available, but on poor pastures or on pastures heavily infested with buttercup, they Toxicity may consume enough to taint milk or to cause cattle to All buttercup species prob- become ill. Occasionally, cattle ably contain the same toxin develop a taste for buttercup called protoanemonin. The and consume fatal quantities. amount produced depends on Sheep seem to tolerate more the growth stage and species of protoanemonin than cattle, and buttercup. to derive substantial early Protoanemonin isn’t highly spring feed from native butter- Figure 1.—Creeping buttercup is a toxic. Actual toxicity depends cups growing on hillside pas- perennial that spreads by stems that root on amount ingested, stage of tures. at nodes. growth, species of buttercup, Larry C. Burrill, Extension weed scientist emeritus, Oregon State University.

A Pacific Northwest Extension Publication • Oregon • Idaho • Washington Table 1.—Characteristics of common buttercups in the Pacific Northwest.

Name Life cycle Distribution Growth habit

Creeping buttercup Perennial West of the coast range and Often creeping, (R. repens L.) occasionally in wet areas rooting at nodes elsewhere in the PNW

Crowfoot buttercup Annual East of Cascades in semiaquatic, Erect, up to 2 feet (R. sceleratus L.) often brackish areas

Bur buttercup Annual East of Cascades, roadsides, Erect, up to 7 inches (R. testiculatus Crantz) cropland

3 Corn buttercup Annual Sparingly distributed Erect, up to 1 ⁄4 feet (R. arvensis L.) in region

Western field Perennial Western OR, WA Erect, 6 to 18 inches buttercup (R. occidentalis Nutt.)

Tall buttercup Perennial Pastures east and west of Erect, up to 3 feet (R. acris L.) Cascades

Birdfoot buttercup Perennial Wetland west of Cascades. Erect, up to 2 feet (R. orthorhynchus Hook.) One variety is found east of Cascades.

Roughseed buttercup Annual, West of Cascades. One variety Erect, up to 1 feet (R. muricatus L.) sometimes is found east of Cascades. perennial

a The drawing of tall buttercup is reproduced, with permission, from C. Leo Hitchcock and Arthur Cronquist, Vascular Plants of the Pacific Northwest, Part 2: Salicaceae to Saxifragaceae, Publications in Biology vol. 17 (Seattle: University of Washington Press, 1990); © 1964 by University of Washington Press. The other drawings are

Identification deeply cut into long, narrow nodes. Leaf blades are divided divisions. Individual fruits are into three toothed lobes Buttercup flowers are mostly small, usually horned, hooked, attached to long stalks, and yellow, regular, and showy, or beaked, and arranged in a they’re hairy. Flowers have 5 or commonly with 5 petals but head. up to 10 shiny yellow petals on occasionally with up to 10 Creeping buttercup is a long stalks. (Figure 3). Leaves are com- perennial that spreads by seeds A second variety (R. repens monly three- or five-parted or and by stems that root at lower var. pleniflorus Fern.) has double Leaves Fruita

1 Long stalks, blades lobed or divided ⁄8 inch long, flattened, rounded, with short back- into three segments. ward-turned beak. Individual fruits shown for other species are arranged on a small head as shown here for creeping buttercup.

1 Long stalks, cut into three to five ⁄10 inch, small, smooth, scarcely beaked. toothed lobes.

All basal, somewhat woolly to several Elongated woolly head, fruits woolly; stiff, parted, divisions narrow, all withered slightly curved beak. by time fruit is mature.

Basal and lower leaves have long Fruits spiny with stiff beak. stalks. Blade cut into narrow toothed divisions. Sometimes first leaves are scarcely divided.

1 From base of plant, long stalked, blade ⁄8 inch, curved beak, smooth. with three main lobes.

Lower leaves three to five deeply cut Flat with short, broad beak. lobes, sharply toothed; upper leaves reduced to three to four narrow segments.

Mostly basal, long stalked. Blades cut Beak on fruit is long, narrow, and straight. into narrow divisions that are toothed. Stem leaves are similar but smaller.

Leaves have three to five toothed lobes, 1⁄4 inch with smooth border, stout awned but cuts aren’t deep. Leaf stalks about beak, and spiny surface. same length as leaf. Leaves are often withered at flowering.

flowers with 10 or more petals; sepals to distinguish the fami- both have showy yellow flowers it’s less common in the Pacific lies (sepals are the outermost and favor wet places. Silverweed Northwest. Table 1 offers help set of flower leaves). Members or cinquefoil (Potentilla anserina with buttercup identification. of the rose family have fused L.) is found mainly east of the Plants that resemble butter- sepals; sepals of the buttercup Cascades; Pacific silverweed cups. Some plants in the rose family are free from each other. (P. pacifica Howell) grows in family can be confused with the Members of the Potentilla coastal areas. buttercups. However, when genus are most likely to be con- flowers are present, use the fused with buttercups because Control Photographs courtesy of Robert Hawkes. Use herbicides Creeping buttercup is seen Pacific Northwest Extension Publications contain material written and produced for mostly as a problem in pas- safely! public distribution. You may reprint writ- tures, so this publication dis- • Wear protective clothing and ten material, provided you do not use it to cusses controls only in a endorse a commercial product. Please safety devices as recom- reference by title and credit Pacific North- pasture environment. mended on the label. Bathe west Extension Publications. To reproduce material used with permission on page 3 in • Most livestock owners seem or shower after each use. this publication, please contact the original unaware that buttercup is an • Read the herbicide label— source. undesirable plant. It’s com- even if you’ve used the herbi- Pacific Northwest Extension Publications monly allowed to increase cide before. Follow closely are jointly produced by the three Pacific until livestock become ill or the instructions on the label Northwest states—Oregon, Washington, die. (and any other directions you and Idaho. Similar crops, climate, and topography create a natural geographic • Most pasture management have). unit that crosses state lines. Since 1949 the techniques such as competi- • Be cautious when you apply PNW program has published more than tive planting, close mowing, herbicides. Know your legal 450 titles. Joint writing, editing, and pro- duction have prevented duplication of or controlled grazing aren’t responsibility as a pesticide effort, broadened the availability of faculty effective against creeping applicator. You may be liable specialists, and substantially reduced the buttercup. for injury or damage result- costs for participating states. • Because it’s a creeping peren- ing from herbicide use. Published and distributed in furtherance of nial, it grows low enough to the Acts of Congress of May 8 and June 30, escape control by mowing. 1914, by the Oregon State University Exten- cides. Not all herbicide labels sion Service, Washington State University The continual movement and Cooperative Extension, the University of rooting of stems allows but- permit the same uses, even Idaho Cooperative Extension System, and tercup to gradually invade those with the same active the U.S. Department of Agriculture cooper- even the densest pasture. ingredient. Be sure the label of ating. • Buttercup is so irritating that the product you’re considering The three participating Extension Services it’s avoided by grazing ani- permits use on the intended offer educational programs, activities, and materials—without regard to race, color, mals; thus, it’s given an site. religion, sex, sexual orientation, national advantage over pasture spe- No herbicide may be used on origin, age, marital status, disability, and cies that are closely grazed. a site or crop for which it’s not disabled veteran or Vietnam-era veteran sta- labeled. However, the absence tus—as required by Title VI of the Civil Mechanical. Creeping butter- Rights Act of 1964, Title IX of the Education of a particular weed from the cup is easy to kill by cultivation Amendments of 1972, and Section 504 of label doesn’t prevent use of the the Rehabilitation Act of 1973. The Oregon if the ground can be worked up herbicide on that weed. State University Extension Service, Wash- and tilled several times during ington State University Cooperative Exten- Herbicide registrations a fallow period. New plants sion, and the University of Idaho Coopera- change frequently; therefore, tive Extension System are Equal Opportu- will appear from seed when the this publication doesn’t contain nity Employers. Published September 1994, land is again used as a pasture. reprinted January 1996. specific herbicide recommenda- Most of the pastures infested $1.00/$1.00/$1.00 tions. Registered uses are sum- with creeping buttercup are in marized each year in the Pacific coastal areas where the land Northwest Weed Control Hand- rarely gets dry enough to make book. repeated tillage an option. In addition, detailed instruc- Chemical. Creeping butter- tions for herbicide use are cup can be controlled in provided on herbicide con- pastures containing grasses or tainer labels and in other litera- clovers by using selective herbi- ture provided by herbicide manufacturers.