Buttercup ground cover, most commonly Ranunculus repens, is a perennial plant often valued for its ability to quickly cover open ground. While its bright yellow flowers and low-growing habit may appear charming, this plant is highly vigorous in garden and lawn settings. Understanding its rapid spread, identifying features, and potential toxicity is crucial for anyone managing this pervasive species.
Identifying Characteristics and Common Species
The most frequently encountered buttercup ground cover is Creeping Buttercup (Ranunculus repens), easily recognized by its distinctive foliage and flowers. Its dark green leaves are divided into three deeply lobed, toothed leaflets, often featuring pale, blotchy markings near the center. The leaves and stems are generally fuzzy or covered in fine hairs.
The plant produces bright, glossy yellow flowers, usually with five petals, appearing from late spring into summer. A defining characteristic is its spread via specialized horizontal stems called stolons or runners, which creep along the soil surface. These runners root easily at their nodes, establishing new, independent plants.
Growth Preferences and Aggressive Spread
Creeping Buttercup is highly adaptable but thrives in heavy, wet, or poorly drained soils, often colonizing areas with standing water or compacted earth. Though it prefers partial shade, it tolerates a wide range of light conditions, from full sun to nearly full shade. This adaptability makes it a formidable competitor in various landscapes.
The primary mechanism for its aggressive spread is vegetative reproduction through its stolons. These runners grow rapidly, rooting at multiple points along their length to create dense mats of new plants. A single plant can spread over a considerable distance in a year, efficiently outcompeting less vigorous plants by consuming soil nutrients. The plant also reproduces sexually, producing seeds that can remain viable in the soil for up to five years, contributing to persistent reinfestation.
Toxicity Concerns for People and Pets
Buttercups contain ranunculin, a compound that serves as a natural defense mechanism. When the plant’s tissues are crushed or chewed, ranunculin is converted by an enzyme into protoanemonin, a toxic, acrid oil. This substance causes irritation and blistering upon contact with skin or mucous membranes.
For humans, contact with the sap can result in dermatitis, characterized by burning, itching, and blisters. Ingestion, though rare due to the plant’s bitter taste, can lead to severe gastrointestinal upset, including vomiting and diarrhea. The greatest concern is for livestock and pets, where consuming fresh leaves can cause excessive salivation, blistering in the mouth, and symptoms of colic. However, the toxicity is short-lived because protoanemonin breaks down when the plant is dried, meaning buttercup found in hay typically poses no threat.
Strategies for Control and Removal
Effective management of buttercup ground cover requires a multi-pronged, persistent approach due to its tenacious growth habit and ability to regrow from fragments. Mechanical removal is highly effective for small infestations, but it must be meticulously executed by digging out the entire root system and all attached stolons. Manual removal is best undertaken when the soil is moist, as this makes it easier to lift the dense, fibrous roots completely without leaving small pieces behind that could regenerate.
Cultural control methods focus on modifying the growing environment to make it less favorable. Since the plant thrives in damp conditions, improving soil drainage through aeration or amending heavy clay soil will discourage its establishment. Applying a thick layer of organic mulch, approximately 8 inches deep, can smother existing plants and prevent new seedlings from emerging.
For widespread infestations, chemical control using a selective broadleaf herbicide is often necessary to avoid killing surrounding lawn grasses. Products containing active ingredients like MCPA or triclopyr are effective against this perennial weed. They should be applied when the buttercup is actively growing in the spring or fall. Removed plant material should be disposed of in municipal yard waste rather than home compost, as the stolons and seeds can survive and contaminate the compost.