Lamium galeobdolon, commonly known as yellow archangel, golden dead-nettle, artillery plant, or aluminium plant, is a widespread wildflower in Europe, and has been introduced elsewhere as a garden plant. It displays the zygomorphic flower morphology, opposite leaves, and square stems typical of the mint family, Lamiaceae.
Description
Lamium galeobdolonsensu lato is a large-leaved perennial plant growing from 15 to 60 cm (6 to 24 in) tall. The paired opposite leaves are stalked with toothed margins. The leaves may or may not have silvery markings (an important character used to distinguish subspecies). The inflorescence is a pseudo-whorl of 4–16 flowers (called a verticillaster) clustered around the axil of a leaf-pair. The calyx is five-lobed and the corolla is yellow with a prominent hood. The flower’s lower lip has three lobes with the central lobe often streaked with orange. There are two short stamens and two long ones. A pair of fused carpels give rise to a four-chambered schizocarp.[3][4]
Identification
Subspecies of Lamium galeobdolonsensu lato are the only taxa in the genus with yellow flowers. All of the subspecies are stoloniferous except subsp. flavidum. The invasive subsp. argentatum is readily distinguished by its silvery white variegated leaves. Lamium galeobdolon subsp. galeobdolon and subsp. montanum can be difficult to distinguish but assuming the plant in question is in full flower, subsp. galeobdolon has a maximum of six (rarely seven) flowers per verticillaster while subsp. montanum averages ten flowers per verticillaster.[5]
Lamium galeobdolon subsp. flavidum is characterized by the lack of stolons, frequently branched fertile stems with upright flowering lateral shoots, and 10–16 small flowers per verticillaster.[3][6] An identification key for the remaining taxa follows:[7]
Identification Key Lamium galeobdolonsensu lato in Central Europe
1a. Leaves and bracts (except for the uppermost) with a distinct silvery pattern (two flexuous bands along the midrib) persisting year around, bracts with wide apical teeth; flowers relatively large
Lamium galeobdolon subsp. argentatum
1b. Leaves generally without silvery pattern (if present, then never forming two continuous flexuous bands along the midrib); apical teeth of bracts mostly narrower; flowers relatively smaller
2
2a. The uppermost bracts ovate, generally less than twice as long as wide, with more-or-less equally distributed marginal teeth, apical tooth short and obtuse, lowermost bracts narrower or only slightly wider than the uppermost ones; the uppermost leaves shortly petiolate; verticillasters few-flowered (maximum number of flowers usually 4–7)
Lamium galeobdolon subsp. galeobdolon
2b. The uppermost bracts lanceolate, more than twice as long as wide, marginal teeth towards the apex more separated, apical tooth long and acute; lowermost bracts mostly distinctly wider than the uppermost ones; the uppermost leaves with longer petioles; maximum number of flowers in verticillasters generally 6–14
Lamium galeobdolon subsp. montanum
Other taxa in the group can have marked leaves but those of subsp. argentatum are distinctive:[8]
Permanent silvery pattern on leaf lamina in L. argentatum always forms two flexuous bands along the midrib, mostly not interrupted by the lateral veins. They are distinctive particularly from the late autumn to the early spring when a contrast brownish-maroon colouring develops on the abaxial side and extends to the midrib-zone of the upper leaf side. Although variegated leaves were frequently observed in all other taxa in our study, they never matched the description above. Silvery-grey markings constituted merely separate splashes or flecks (small-sized in L. montanum and L. flavidum, larger in L. galeobdolon), not merged into continuous bands. Thus, a combination of two distinct silvery flexuous bands together with a strong chocolate-maroon zone along the midrib in winter can be regarded as specific L. argentatum markers.
— Rosenbaumová, Plačková & Suda (2004)
In particular, a cultivar of subsp. flavidum known as 'Hermans Pride' has silver-spotted leaves,[9] but even though the markings are unlike those of subsp. argentatum, the two taxa are sometimes confused.
The base chromosome number of taxa in genus Lamium is x = 9.[10]Lamium galeobdolon subsp. flavidum and subsp. galeobdolon are diploid (2n = 2x = 18) while subsp. argentatum and subsp. montanum are tetraploid (2n = 4x = 36). A few triploid individuals have been reported.[11] The triploids are thought to be natural hybrids between diploid subsp. galeobdolon and tetraploid subsp. argentatum.[12]
Taxonomy
Lamium galeobdolon was first described as Galeopsis galeobdolon by the Swedish botanist Carl Linnaeus in 1753.[13] Linnaeus himself placed Galeopsis galeobdolon in the genus Lamium in 1759, and therefore the correct name is Lamium galeobdolon(L.) L.[1][14]
Most authorities recognize four closely-related taxa, either as subspecies of Lamium galeobdolon,[2][15][16] or as full species in genus Lamium,[3] in which case the group of taxa is referred to as Lamium subgen. Galeobdolon.[17] Some authorities segregate the species into other genera (either Galeobdolon or Lamiastrum) but genus Lamium remains monophyletic in any case.[18]
Lamium galeobdolon subsp. argentatum was first described as Galeobdolon argentatum by the Czech botanist Miroslav Smejkal in 1975.[19] In a comprehensive and influential treatment of genus Lamium published in 1989,[20] the Dutch botanist Jacob Mennema reduced the species to forma and placed it in synonymy with Lamium galeobdolon subsp. galeobdolon. Hence subsp. argentatum was neglected for a long time and its invasion history is poorly documented.[21]
Most North American authorities recognize a single taxon, referred to as Lamium galeobdolon or Lamiastrum galeobdolon.[22][23][24] Following the taxonomy of Mennema, flora authors refer to either Lamium galeobdolonsensu lato or Lamium galeobdolon subsp. galeobdolon.[25][26][27]Lamium galeobdolon subsp. argentatum is not recognized in North America.
There are a number of closely related taxa that hybridize with L. galeobdolon and in some cases are not unequivocally accepted as distinct species but considered subspecies or varieties by many authors.[citation needed] Most well known among these is variegated yellow archangel (subsp. argentatum), whose leaves often have variegation, showing as silver patches arranged as a wide semicircle. This, and in particular its large-flowered and even stronger-marked cultivar 'Variegatum', is the taxon most often met with as a garden escapee.
Etymology
Both the generic name Lamium and the specific name galeobdolon were used by Pliny the Elder in the first century AD.[28] The name galeobdolon has several possible interpretations.[29] It may come from the Greek words galen meaning "weasel" and bdolos meaning "fetid smell". Hence the common name yellow weasel-snout.[30]
Distribution
It is native to Europe, and found throughout Europe and Western Asia.[31]
Lamium galeobdolon subsp. argentatum spreads easily and so has been commonly used as an ornamental ground cover. It can be invasive in places where it is not native.[33] In Europe, subsp. argentatum has aggressively outpaced native subspecies in several countries.[34] For example, in Basel, Switzerland, subsp. argentatum tripled its occurrence in four decades while exhibiting "a higher growth rate and regeneration capacity" than the native subsp. galeobdolon.[35]
Based on morphological characters, number of chromosomes, pattern of geographical distribution, and phytochemistry, early botanists hypothesized that the tetraploid subsp. montanum originated as a hybrid between the two diploid taxa, subsp. flavidum and subsp. galeobdolon.[36] However, more recent phylogenetic data suggests that subsp. montanum originated from subsp. flavidum alone. Similarly, there is conflicting evidence regarding the origins of the tetraploid subsp. argentatum suggesting that it may or may not have originated from subsp. galeobdolon alone.[37]
Gallery
Botanical illustration by Johann Georg Sturm (1796)
Flower cluster with yellow petals, hooded flowers, and unequal stamens
Leaves with silvery white variegated markings growing in Jūrmala, Latvia
Cluster of plants with yellow flowers and silvery white variegated leaves
^ abcMeyer, Thomas. "Taubnesselarten mit gelber Krone" [Deadnettle species with yellow crown]. Flora-de: Flora of Germany (in German). Retrieved 16 March 2024.
^"Lamium galeobdolon". Manual of the Alien Plants of Belgium. Retrieved 20 March 2024.
^Weakley, Alan S.; Southeastern Flora Team (2024). "Lamium galeobdolon(Linnaeus) Linnaeus". Flora of the southeastern United States. University of North Carolina Herbarium, North Carolina Botanical Garden. Retrieved 16 March 2024.
Bendiksby, Mika; Brysting, Anne K.; Thorbek, Lisbeth; Gussarova, Galina; Ryding, Olof (August 2011). "Molecular phylogeny and taxonomy of the genus LamiumL. (Lamiaceae): Disentangling origins of presumed allotetraploids". Taxon. 60 (4): 986–1000. JSTOR41317321.
DeFelice, Michael S. (2005). "Henbit and the Deadnettles, Lamium spp.: Archangels or Demons?". Weed Technology. 19 (3): 768–774. JSTOR3989505.
Gilman, Arthur V. (2015). New Flora of Vermont. Memoirs of The New York Botanical Garden, Volume 110. Bronx, New York, USA: The New York Botanical Garden Press. ISBN978-0-89327-516-7.
Haines, Arthur (2011). New England Wild Flower Society's Flora Novae Angliae: A Manual for the Identification of Native and Naturalized Higher Vascular Plants of New England. Illustrated by Elizabeth Farnsworth and Gordon Morrison. Yale University Press. ISBN978-0-300-17154-9.
"Lamium galeobdolon". New Zealand Plant Conservation Network. Retrieved 20 March 2024.
Ellis, R. Gwynn, ed. (September 1987). "Variegated archangels"(PDF). B.S.B.I. News. 46. Cardiff: Dept. of Botany, National Museum of Wales: 9–11. Retrieved 26 March 2024.
Botanical illustration by Johann Georg Sturm (1796)
Leaves with silvery white variegated markings growing in Jūrmala, Latvia
Cluster of plants with yellow flowers and silvery white variegated leaves
Plants with yellow flowers growing in Hungary
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