Yellow Archangel, Yellow Deadnettle, and Yellow Weaselsnout.
General: Yellow Lamium is an evergreen, perennial groundcover that can grow trailing or upright over low-growing vegetation.
Flowers: Small and yellow with orange or brown markings on them. Flowers have hooded upper petals and a lipped lower petal. Together, they form into four nutlets, each containing one seed.
Stems: Hairy, erect, and four-sided (square) stems can grow 30 – 60 cm tall.
Leaves: Leaves are variegated with green and silver, including a grey outer margin. They have tapered edges and are oval-shaped.
Fruit: Each flower produces four small nuts (nutlets), with each nutlet containing one seed.
Roots: The plant has a shallow root system and produces stolons (roots that grow horizontally).
Goutweed, Bishop’s Weed, or Ground Elder (Aegopodium podagraria) can be differentiated from Yellow Lamium by its leaves that grow in groups of 3. It also has white flowers arranged in umbels or umbrella-shaped clusters.
Herman’s Pride (Lamium galeobdolon var.) has smaller, narrower, and more coarsely serrated leaves in comparison to Yellow Lamium.
Habitat and Origin
Yellow Lamium is native to Europe and was introduced to North America as a garden ornamental. While this species is found in a wide range of light conditions and a variety of soil types, it tends to prefer habitats with full shade and moist soils that are rich in organic matter. Therefore, Yellow Lamium is often spotted in ravines, greenbelts, forested areas, and parks. Due to its popularity as a hardy groundcover, this plant is also typically found in gardens, along ornamental borders, or as a component of hanging baskets.
Propagation & Vectors of Spread
Yellow Lamium can propagate vegetatively and by seed. Vegetative propagation occurs through the stolons, as well as through root and stem fragments. If a root or stem fragment touches the soil, it can sprout into an entirely new plant. Seed propagation, however, tends to be less common for this species.
Since Yellow Lamium is a popular choice for an ornamental groundcover, it often spreads to new areas as a garden escapee. Plant and stem fragments are easily dispersed by wind and people. One way invasive plants such as Yellow Lamium are spread to new places is through the dumping of garden waste into natural areas. The stolons, which can spread up to 1 metre per year, crawl underneath fences into parks, ditches, forested areas, and other natural settings. Seeds can be spread by wind, water, and animals. For instance, ants have been recorded transporting seeds up to 70 m away from the parent plant.
Ecological and Economic Impacts
- Outcompetes native species by blocking sunlight and therefore reducing photosynthesis, as well as restricting space availability with its extensive root system.
- Reduces the diversity of native vegetation and ultimately alters the structure of plant communities, especially in woodland understories and riparian ecosystems.
- Provides poor shelter and reduces food availability for livestock and local wildlife, including pollinator species that rely on a diverse plant community.
- Can displace shade-tolerant agricultural crops and reduce yield.
What Can I Do?
Yellow Lamium can be found throughout the Sea to Sky Region, so PREVENTION is key:
Learn to identify Yellow Lamium: use the images presented in this profile page to learn how to identify Yellow Lamium.
What to do if you spot it: You can report any Yellow Lamium sighting by clicking here.
- Regularly monitor properties for weed infestations.
- Ensure soil and gravel are uncontaminated before transport.
- Check wildflower mixes to ensure that they do not contain Yellow Lamium.
- Ensure that all plant parts, including floral arrangements, are bagged and disposed of properly in the household stream. Do not compost, as any seeds present are likely to survive the composting process.
- Ensure that all stem and root fragments are removed when controlling Yellow Lamium, as these fragments can sprout into new plants.
- Purchase Yellow Lamium from a garden centre or nursery.
- Cut or mow Yellow Lamium, as new plants can sprout from root or stem fragments.
- Unload, park or store equipment or vehicles in infested areas; remove plant material from any equipment, vehicles or clothing used in such areas and wash equipment and vehicles at designated cleaning sites before leaving infested areas.
- Plant Yellow Lamium in a garden, no matter how well-contained its enclosure may seem.
- Move soil, fill, or gravel that has been contaminated with Yellow Lamium.
- Since Yellow Lamium has relatively shallow roots, hand-pulling tends to be a relatively effective method. However, care should be taken to remove as many plant fragments as possible, as any root and stem fragments could sprout into new plants.
- Aim to remove as much of the root system as possible, which may be easiest to do in the early spring when the soil is moist.
- Sites should be monitored every year for re-growth after any mechanical removal.
- Glyphosate, triclopyr, or imazapyr have been recorded as effective herbicides for this species. Tank mixtures of glyphosate and either triclopyr or imazapyr has been shown to be more effective than single-product applications.
- An addition of a surfactant to either triclopyr or glyphosate appears to also be effective.
- Applications should occur during the fall and spring when Yellow Lamium is most active, but before the blooming period in the spring to reduce any impacts on pollinators.
- Multiple treatments may be required and monitoring following a chemical treatment is recommended.
- We recommend that any herbicide application is carried out by a person holding a valid BC Pesticide Applicator Certificate. Before selecting and applying herbicides, you must review and follow herbicide labels and application rates; municipal, regional, provincial and federal laws and regulations; species-specific treatment recommendations, and site-specific goals and objectives.
There is no biocontrol available for Yellow Lamium at this time.
- BC Field Guide to Noxious Weeds and Invasive Plants, https://bcinvasives.ca/documents/Field_Guide_to_Noxious_Weeds_Final_WEB_09-25-2014.pdf
- E-Flora BC, http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Lamium%20galeobdolon
- Invasive Species Council of British Columbia (ISCBC), https://bcinvasives.ca/invasive-species/identify/invasive-plants/yellow-archangel
- Invasive Species Council of Metro Vancouver, Best Practices for Yellow Archangel in the Metro Vancouver Region, http://www.metrovancouver.org/services/regional-planning/PlanningPublications/YellowArchangelBMP.pdf
- King County, https://www.kingcounty.gov/services/environment/animals-and-plants/noxious-weeds/weed-identification/yellow-archangel.aspx
- Washington State Noxious Weed Control Board, https://www.nwcb.wa.gov/images/weeds/Lamiastrum-galeobdolon.pdf