- Latin synonym: Lamium galeobdolon
- Family: Mint Family – Lamiaceae (Labiatae)
- Growing form: Perennial herb. Runners big-leaved.
- Height: 20–40 cm (8–16 in.).
- Flower: Corolla irregular (zygomorphic), yellow, 15–25 mm (0.6–1 in.) long, fused, bilabiate, long-tubed. Upper lip high, convex; lower lip 3-lobed, all lobes almost equally large, central lobe triangular, tapered. Calyx almost regular (actinomorphic), 5-lobed. Stamens 4, of which 2 short and 2 long. Gynoecium composed of 2 fused carpels. Flowers in whorls forming an interrupted spike.
- Leaves: Opposite, stalked. Blade broadly ovate, blunt or shallowly cordate-based, net-veined, mostly lightly spotted, underside often dark violet, with toothed margin. Subtending bracts like stem leaves.
- Fruit: 4-parted schizocarp.
- Habitat: Parks, gardens, woods, broad-leaved forests. Ornamental, left over and escape from old gardens.
- Flowering time: May–September.
Pretty yellow archangel can be found in Finland around the edges of old gardens and parks, where it grows as an escape or left-over. It can survive without any care or attention for decades and even slightly enlarge its area. With the help of limp runners it can spread to form stands that cover several square metres. Species can be found in the wild, mainly in Estonia and on the Karelian isthmus on rich river-bank broad-leaved thickets and woods. Different varieties that have coloured leaves are more popular as ornamentals than pure yellow archangel. Plants that grow in Finland often have white patches, but in gardens there are entirely silver-leaved yellow archangels. All of these have large, butter-yellow flowers in compact whorls.
Yellow archangel has been bounced around from one genus to the next: Linné regarded it first as a member of genus Hemp-nettle (Galeopsis), and in the meantime it has also been considered to belong to genus Dead-nettle (Lamium). It is currently classified in a genus of its own. More visible differentiating identification marks are the corolla’s yellow colour and the clearly three-lobed lower lip. There is no danger of mixing it up with other deadnettles that grow in Finland as weeds. Of the plants that grow in Finland, it perhaps bears the most resemblance to large-flowered hemp-nettle (Galeopsis speciosa), although this plant has uniformly coloured light-green feather-veined leaves and a violet patch on the lower leaf of the corolla.