Purple Dead-Nettle

Purple Dead-Nettle (Lamium purpureum)

Report

Photo credit: J. Hallworth

Management Category

Synonyms

Red deadnettle, purple archangel, dead nettle

ID Characteristics

Flowers: The small red-purple or pink flowers are tubular, and the upper lobe is usually darker than the lower one. The upper and lower petals incline toward each other. The flowers form axillary clusters (attached at the juncture of stems and leaf stalks). They are arranged in false whorls of 3-6 flowers.

Stem: Stems are square, about 30 cm tall and bear pairs of leaves that grow opposite one another.

Leaves: The leaves don’t have stinging hairs like other nettles. They densely crowd the stem and each pair rotates 90 degrees from the pair of leaves immediately below or above. The young leaves at the apex of the stem are tinted purple and become dull green when mature.

Fruit: Purple dead-nettle flowers produce four reddish-brown nutlet seeds. Distinctive dark lines run down the centre of each nutlet face and around the outside.

Roots: The roots are shallow and fibrous.

Similar Species

Native

Self-Heal (Prunella vulgaris var. lanceolate): The leaves of self-heal may be slightly toothed or entirely round, and the leaves are not purple. The many flowers of self-heal occur in a single inflorescence above the upper leaves.

360px-Common_self-heal_Prunella_vulgaris_-_leaf

By Jesse Taylor – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=20255993

Invasive

Common dead-nettle (Lamium amplexicaule) has stemless leaves.

Common Dead-Nettle John D. Byrd, Mississippi State University, Bugwood.org

Habitat and Origin

Purple dead-nettle is native to Europe and Asia. It was introduced to North America through the horticultural trade. It now grows in southern British Columbia and eastern Canada.

Purple dead-nettle grows well in disturbed areas. It grows in areas with full sunlight or light shade and moist, fertile soil. It can be found in gardens, orchards, fields, ditches, and weedy edges of woodlands.

How It Spreads

Purple dead-nettle spreads through both seeds and vegetative methods. Flowers can self-pollinate before opening but can also be cross-pollinated by bees and wasps. Roots can form new genetically identical plants by creeping (via horizontal roots growing outwards from the main plant and sending up clones) or by forming new plants from root fragments. Purple dead-nettle can germinate year-round when buried at depths of 0.5 – 2 cm. One plant generally produces 300 seeds (but up to thousands!), which persist in the soil for several years.

Purple dead-nettle is sometimes sold for ornamental purposes, so the nursery trade and gardeners are considered the plant’s main vector of spread. Purple dead-nettle is also spread in contaminated soil and by dumping garden waste.

Impacts

Ecological:

Outcompetes native plants by forming dense ground cover shading out native species.
Reduces available space, nutrients and water available for other vegetation.
Reduces biodiversity

Economic:

Reduces crop yields.

Stop the Spread

There is insufficient information about Purple dead-nettle’s distribution, impacts, potential for spread and feasibility for control in the Sea to Sky. If you see Purple dead-nettle’s, please report it.

Learn to identify Purple dead-nettle: use the images on this profile page to learn how to identify Purple dead-nettle.

What to do if you spot it: You can report any Purple dead-nettle sighting visiting our reporting page.

DO:

Regularly monitor properties for weed infestations.
Ensure soil and gravel are uncontaminated before transport.
Check wildflower mixes to ensure that they do not contain Purple Dead-Nettle.
Ensure plants are disposed of in a garbage bag if found in floral arrangements to prevent seeds from spreading.

DO NOT:

Do not 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.
Do not plant Purple Dead-Nettle in a garden, no matter how well-contained its enclosure may seem.
Do not move soil that has been contaminated with Purple Dead-Nettle.
Do not compost!

Control

Mechanical

Purple dead-nettle can be pulled up by hand before it goes to seed.
Regular mowing/tilling will reduce weed progression, but won’t eradicate the plant.
All plant parts must be bagged and deeply buried in a landfill; if plant fragments are left on site, Purple dead-nettle is likely to re-establish.
When tilling, be sure to prevent machinery from spreading root fragments to new sites.

Chemical

Purple dead-nettle can be controlled with metsulfuron.
Fall and early spring applications are generally the most effective and may also suppress seed production.

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.

Biological

There are no biocontrol agents available in BC for this plant.