Creeping buttercup identification and control
Creeping buttercup, a King County Weed of Concern, is a low-growing perennial with creeping stolons that's found in rural and urban areas throughout King County, such as pastures, farmlands, natural wetlands, city gardens, and lawns. Stems reach one foot tall. Leaves are dark green with pale patches, divided into 3 toothed leaflets. Leaves and stems are both somewhat hairy. March-August, produces bright yellow, glossy flowers with usually 5 (up to 10) petals. Reproduces by seed and vegetatively via long, branching stolons that root at the nodes. Stolon growth starts in spring, peaks in late summer. This plant is extremely aggressive and toxic to grazing animals.
Legal status in King County, Washington
Creeping buttercup is not on the Washington State Noxious Weed List. However, in King County, this non-native invasive buttercup species is classified as a Weed of Concern. For more information see Noxious Weed Lists and Laws.
The King County Noxious Weed Control Board recommends the prevention of spread of this species to uninfested areas and its control in protected wilderness areas, natural lands that are being restored to native vegetation, and in pastures that are being grazed.
- Perennial with short swollen stems and creeping stolons that root at the nodes
- Can be distinguished from other buttercup species such as tall buttercup (Ranunculus acris) by the creeping stolons
- Can grow up to one foot tall but are often shorter in mowed areas
- Leaves are dark green with light patches and are divided into three toothed leaflets, the central leaflet on a stalk
- Pale patches on the leaves distinguish creeping buttercup from similar looking plants such as hardy geraniums
- Basal leaves have long petioles (stalks), leaves higher up the plant have shorter or no petioles
- Leaves and stems are somewhat hairy
- Flowers usually have five (sometimes ten) glossy, bright yellow petals and grow singly on long grooved stalks
- Bloom time is usually from March to August
- Fruits are clusters of 20-50 achenes on globe-shaped heads. Achenes have a short hooked beak and are light brown to blackish brown when mature with an unevenly pitted surface
Fresh buttercup plants are toxic to grazing animals, who can suffer from salivation, skin irritation, blisters, abdominal distress, inflammation, and diarrhea. Fortunately, buttercup has a strong, bitter taste so animals generally try to avoid it if more palatable forage is available. Also, the toxin protoanemonin is not very stable and loses its potency when dry, so buttercup is not generally toxic in hay. Unfortunately, livestock occasionally develop a taste for buttercup and consume fatal quantities. It is safest to keep populations of buttercup under control on grazed pastures and offer plenty of healthy forage.
Creeping buttercup spreads by seed and by long branching stolons that root at the nodes, forming new plants. In more established woodland and grassland communities, this plant increases mostly through stolons unless the soil is disturbed. In dry conditions, flowering and seeding is more prevalent and in wet conditions, stolons are more plentiful. Seeds can germinate and seedlings can grow under water-logged conditions.
Depending on the temperature, creeping buttercup either overwinters as a rosette or dies back to ground level. In either case, the nutrients stored in the short swollen stem produce rapid growth in spring, between April and June. Stolons grow from the leaf axils in spring and summer and growth peaks in late summer. Stolons connecting parent and daughter plants usually die off in fall.
Flowers can appear from March to August with seeds soon after. Each plant produces from about 20 to 150 seeds. Seeds can remain viable in the soil for at least 20 years, and up to 80 years, especially under acid or water-logged conditions. Seeds are dispersed by wind, water, birds, farm animals, rodents, and other animals by adhering to them with the hooked seeds.
Prevention and cultural control
- In lawns and pastures, promote healthy grass by overseeding, fertilizing as needed, and not over-grazing. Adding lime can improve grass health and keep buttercup from re-establishing. However, lime won’t control buttercup that is already well-established.
- It also helps to improve soil drainage. Reduce compaction by aerating and avoid trampling when soils are wet.
- Clean mowers and other equipment to avoid spreading buttercup seeds to un-infested areas.
- Dig out with a sharp trowel or fork-type tool, removing all of the runners, roots and growing points. Digging is most effective from fall to spring while the soil is moist and roots won’t break off as much.
- Cultivating or incomplete digging may increase the buttercup population because it can sprout from nodes along stem and root fragments.
- Disturbance of the soil can increase seed germination. Seeds stay viable for 20 years or more and the number of seeds in infested soils can be immense compared to the number of plants present, especially in long-term pastures and woodland ecosystems.
- Creeping buttercup’s growing point is at soil level, so plants resist mowing and quickly re-sprout when cut.
- Regular cultivation can kill the buttercup but plants buried by cultivation can grow back up through deep soil and re-establish themselves and long-lived seeds in the soil can germinate and re-infest the area once cultivation ceases.
- Herbicides can be used if allowed and appropriate for the site and land use. Follow all label directions to ensure safe and effective use.
- Glyphosate (e.g. Roundup, Aquamaster) can be applied to actively growing plants before they seed. Keep spray off of grass and other plants. Re-seed or re-plant bare areas after removing buttercup to keep it from re-infesting the area.
- Broadleaf herbicides can be applied over grassy areas infested with creeping buttercup to selectively kill the buttercup and not the grass. Products containing the active ingredient MCPA are most effective on buttercup. Metsulfuron (Escort, Ally) is also effective but can harm some grasses. Follow label directions on timing and rates.
- It will probably take at least two or three applications to eradicate creeping buttercup because of the seed bank and because some mature plants will generally recover.
- Monitor the treated area for re-growth and pull up any new seedlings before they establish runners.