Yellow archangel (Lamium galeobdolon)

Synonyms: Galeobdolon luteum, Galeobdolon galeobdolon, Lamiastrum galeobdolon

Common Names: Yellow dead-nettle, golden dead-nettle, yellow weasel-snout

Description:

Yellow archangel (Lamium galeobdolon) is a low, creeping evergreen groundcover in the mint family, native to Europe and western Asia [1][3]. It is sold for its silver-marked leaves and yellow flowers, but it escapes from gardens and forms dense mats in shady woods, crowding out native wildflowers [2][3]. MISIN tracks it because those mats spread fast ? by creeping stems, by dumped cuttings, and by broken fragments ? and offer little food or shelter for native wildlife [3].

Habit:

Yellow archangel is a low, spreading plant about 1 to 2 feet tall with square stems ? the tell-tale sign of the mint family [2]. Its paired (opposite) leaves are oval with toothed edges and are usually marked with silvery-gray patches, the variegated look of the form most often planted [2][3]. Look for it in mid-spring, when small yellow two-lipped flowers ? a hooded upper lip and a lower lip streaked orange to brown ? appear in whorls where the leaves meet the stem [2][3]. Because the plant is evergreen to semi-evergreen, its silver-mottled leaves stand out on the forest floor most of the year, so it is easy to spot even outside the flowering season [3].

At-a-glance cues:

1. Square stems (mint family) on a low, creeping groundcover [2]
2. Paired oval, toothed leaves marked with silvery-gray patches [2][3]
3. Small yellow two-lipped flowers with a hooded upper lip, in whorls along the stem in mid-spring [2][3]
4. Stems creep along the ground and root where the leaf joints touch the soil [2][3]

Leaves:

1. Arrangement: opposite (paired along the stem) [2]
2. Shape: oval to triangular, toothed along the edges [2]
3. Markings: usually variegated, with silvery-gray patches across the surface; undersides can turn purple in cool weather [2][3]
4. Surface: softly hairy [3]
5. Size: up to about 3.5 inches (9 cm) long [4]

Stems:

1. Habit: low, creeping evergreen to semi-evergreen perennial groundcover, about 1 to 2 feet tall [3]
2. Square in cross-section, typical of the mint family [2]
3. Trailing stems root at the leaf joints (nodes) where they touch moist soil [2][3]
4. Green, branching freely to form dense cover [3]

Flowers:

1. Color: yellow, with the lower lip streaked orange to brown [2][3]
2. Shape: two-lipped, with a hooded upper lip and a lower landing lip ? the typical mint-family flower [2]
3. Arrangement: in whorls (rings) where the leaves meet the stem [2]
4. Bloom time: mid-spring [2]

Fruit and seeds:

1. Fruit: small, dry nutlets ? four per flower, typical of the mint family [3]
2. Spread is mostly by creeping stems and fragments; seed plays a smaller role [2][3]

Habitat:

Yellow archangel is native to shaded woodlands and thickets across Europe and western Asia [1]. In North America it is a planted ornamental that escapes into the wild and has become invasive in parts of the Pacific Northwest, the Northeast, and the Mid-Atlantic [3][5]. It grows in sun to deep shade and tolerates dry spells, but it does best in moist, shady ground ? so it most often invades forests, woodland edges, greenbelts, ravines, and streamside (riparian) areas near where it was planted or dumped [3].

Reproduction:

Yellow archangel spreads mainly by its creeping stems [2][3]. The trailing stems root wherever a leaf joint touches moist soil, so a patch widens steadily and a planting can creep well beyond a garden bed [2][3]. The most common way it reaches new places is through people: it is planted as a groundcover and in hanging baskets, and cuttings or whole baskets dumped as yard waste take root and start new infestations [3]. Even a small stem fragment can grow into a new plant, and cutting it back tends to make it grow denser rather than killing it [3].

It also makes seed, but vegetative spread by stems and fragments is the bigger driver [2][3]. For control timing: because it stays green much of the year, you can find and remove it in most seasons, but pulling it before or during spring flowering helps keep a patch from expanding and setting seed [2][3].

Impact and Damage:

In a garden, yellow archangel does not stay where it is planted ? its creeping stems spread into lawns, beds, and neighboring yards, and the dense mat crowds out other plantings [3].

In natural areas it is the bigger concern. It forms thick groundcover mats on the forest floor that outcompete native wildflowers and tree seedlings, and it provides little food or cover for native wildlife [3]. It is especially troublesome in moist woods and along streams, where dumped garden waste often starts it [3]. How aggressive it becomes varies with climate and setting ? it is a serious invader in cool, moist regions but is considered less aggressive in some drier areas [2][3].

Similar species:

Yellow archangel's silver-marked leaves are its main source of confusion, since its yellow flowers set it apart from most other creeping mints.

Spotted dead-nettle (Lamium maculatum) is the closest match ? another low, silver-marked groundcover in the mint family. Tell them apart by the leaf markings and flower color: spotted dead-nettle usually has a silvery stripe down the middle of the leaf and pink-to-purple flowers, while yellow archangel is spotted with silver across the whole leaf and has yellow flowers [4].

Bishop's goutweed (Aegopodium podagraria) is another spreading groundcover often grown in a white-and-green variegated form, so its patterned leaves can be mistaken for yellow archangel from a distance. Up close it is easy to separate: bishop's goutweed has compound leaves divided into leaflets and flat-topped clusters of tiny white flowers, rather than square stems with yellow mint flowers [4].

Monitoring and rapid response:

Signs to watch for:

1. Low mats of silver-marked, paired leaves on square stems, often near gardens or dumped yard waste [2][3]
2. Small yellow two-lipped flowers in whorls along the stem in mid-spring [2][3]
3. Stems creeping outward and rooting at the leaf joints, especially in moist shade [2][3]

What you can do:

1. Pull or dig out the whole plant by hand when the soil is moist, removing all roots and stem fragments ? bits left behind resprout [3]
2. Avoid simply cutting or mowing it; cutting tends to make it grow back denser [3]
3. Smother a patch by covering it with cardboard or heavy mulch through the growing season to block all light [3]
4. Bag every stem, root, and cutting and put it in the trash for the landfill ? never compost it or dump it in natural areas, since fragments start new patches [3]
5. Natural area crews can target outlying patches and dump sites first, then work back toward the source, returning over several seasons to pull regrowth [3]

When to call a professional:

1. Large, well-established mats ? especially in woods or along streams ? that keep regrowing from fragments [3]
2. For chemical control options, contact a licensed applicator or your local cooperative extension office.

Report sightings to MISIN. Help track this species' spread by submitting observations through the MISIN web site or the MISIN mobile app (Android, iOS, Windows, and macOS). Photos at multiple angles paired with a precise GPS location are the most valuable data for confirming new occurrences and triggering rapid-response review.

Credits:

1. Plants of the World Online (POWO), Royal Botanic Gardens, Kew. Lamium galeobdolon (L.) L.. powo.science.kew.org
2. University of Wisconsin?Madison Division of Extension. Yellow Archangel, Lamium galeobdolon. hort.extension.wisc.edu
3. Washington State Noxious Weed Control Board. Yellow Archangel (Lamium galeobdolon). nwcb.wa.gov
4. Long Island Invasive Species Management Area (LIISMA). Yellow Archangel (Lamium galeobdolon). liisma.org
5. USDA NRCS PLANTS Database. Lamium galeobdolon (L.) Ehrend. & Polatschek. plants.usda.gov

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