Story of the Weeds: Tall Buttercup
Weed Name and Identification
Common Name: Tall Buttercup
Scientific Name: Ranunculus acris
Don’t let its sunny yellow flowers fool you, Tall Buttercup is a toxic, unpalatable invader with a particular love for soggy, compacted pasture. In northwest-central Alberta, it’s a common sight in wet meadows, hayfields, and overgrazed pasture corners. It’s often found growing alongside oxeye daisy, another non-native species that signals pasture stress. Tall Buttercup stands tall, up to 90 cm, with glossy yellow flowers (five petals) and deeply lobed leaves that look like a spread hand or a crow’s foot. Unlike some creeping buttercup relatives, Ranunculus acris spreads primarily by seed, although short rhizomes can help it form dense clusters.
What It Indicates About Soil
Tall buttercup tends to thrive in areas with:
Poor drainage or high water tables
Heavy, compacted soils that stay damp in spring
Acidic or low-fertility conditions
Overgrazed or disturbed pastures
Its presence often points to wet ground that’s either naturally saturated (e.g. low-lying areas or spring seeps) or chronically compacted by livestock traffic. In dry years, buttercup tends to fade, but wet seasons bring it roaring back. If you’re seeing a buttercup bloom, it may be time to assess your pasture’s drainage, aeration, and fertility.
Ecological Role
As a pioneer species, tall buttercup fills bare or moist patches quickly. It does offer some erosion control and nectar for pollinators like bumblebees, but large infestations reduce biodiversity by crowding out more productive forage and native plants. In riparian or moist pasture systems, its aggressive growth displaces grasses and legumes that contribute to soil health and feed value.
Livestock Interaction
Palatability: Very low. Livestock, including cattle, horses, sheep, and goats, generally avoid it.
Toxic: Tall buttercup contains protoanemonin, a compound that can cause blistering in the mouth and gastrointestinal distress when eaten fresh. Animals typically avoid it unless forage is severely limited.
Impact on Pasture: Because livestock won’t eat it, buttercup is left untouched, leading to selective grazing of desirable plants, reduced forage quality, and accelerated weed spread.
Hay safety: Dried buttercup loses its toxicity, but doesn’t contribute nutritional value. Hay contaminated with buttercup may also reduce palatability or cause off-flavours in milk.
Management and Replacement Strategies
Prevention
Use weed-free seed and hay
Clean equipment after mowing or haying infested areas
Monitor wet, compacted zones and respond early
Soil and Pasture Management
Test and correct pH: Tall buttercup tolerates acidic soils; apply lime if needed
Improve drainage: Repair seeps, address compaction, and avoid grazing on wet soils
Use rotational grazing: Prevent overgrazing and allow for forage recovery
Fertilize carefully: Tall buttercup can thrive even in rich soils if pastures are poorly managed. Fertility without strong plant competition just feeds the weed.
Cultivation is an option: For severe infestations, ploughing and growing annual crops for a few years can help. Tall buttercup doesn’t survive under cultivation.
Mechanical Control
Mow before flowering to reduce seed production. Repeat as needed; plants may regrow lower to the ground.
Hand-pull small infestations (wear gloves—sap can irritate skin)
Chemical Control
Spot-spray with selective broadleaf herbicides (e.g., 2,4-D, MCPA, or dicamba) before flowering
Follow local guidelines for product selection, timing, and grazing restrictions
Watch for herbicide resistance: Some tall buttercup populations (like in New Zealand) have developed resistance to Group 4 herbicides such as MCPA. Rotate herbicide groups and combine with other control methods to avoid resistance buildup.
Biological Control
No biocontrol agents are currently approved or in use for tall buttercup in Canada
Replacement Forages
Once buttercup is controlled, reseed or overseed with vigorous, competitive species adapted to your conditions:
Moist or compacted soils:
Meadow brome, timothy, or tall fescue (endophyte-free) for dense, grazing-tolerant cover
Alsike clover or birdsfoot trefoil to boost nitrogen and tolerate low pH or moisture
Wet depressions or seeps:
Reed canarygrass (low-alkaloid varieties) for flooded or waterlogged ground
Creeping foxtail – excels in poorly drained soils and creates a sod-forming barrier against buttercup
Tufted hairgrass or alsike clover as moisture-tolerant diversity options
Short-term suppression before reseeding:
Use Italian ryegrass or annual oats for fast cover and weed competition in a single season. These can be cut, grazed, or used as a transition to perennial forage without contributing to the buttercup seedbank.
By improving soil conditions and establishing strong, competitive forage, tall buttercup can be crowded out and kept from returning.
Sources and Further Reading
One Page Guide
