(Editor's Note: This article was originally published on March 11, 2008. Your comments are welcome, but please be aware that authors of previously published articles may not be able to promptly respond to new questions or comments.)
It's a story that will be sadly familiar to most gardeners. I was looking for a groundcover. There is a north-facing area under a deep overhang of the eaves where nothing would grow. I had tried one plant after another, only to watch them all languish in such a desolate spot. Then, one fatal day, I saw this attractive plant at the nursery. The label said: Will thrive even in dry shade where nothing else will grow. With a glad cry of rejoicing, I bought a flat of Yellow Archangel and bore it home to plant in my problem area.
Yes, I should have known. Because the nature of groundcovers is that they spread. And because a plant that will thrive even in harsh conditions is likely to thrive even more vigorously in better conditions. So it was with the Yellow Archangel. It did indeed thrive in the dry shade, but it was quick to discover the slightly sunnier, slightly moister conditions just a few feet away beyond the overhang, and rapidly spread into the midst of the Cranesbill geraniums and azaleas, where I have been fighting it ever since.
Archangel spreads by sending out multiple stolons, or runners, that root at the joints. A runner can grow several feet in the course of a year. What makes this plant particularly hard to control or eradicate is the fact that the stems break off when you try to dig them up, leaving the root to resprout. It seems to have an evil genius for insinuating itself into the roots of, say, an azalea, limiting the use of hoes or other such implements of destruction. It also spreads readily by seed.
Yellow Archangel was originally classified as a member of the Lamium genus, but the botanists, who can not seem to leave well enough alone, have lately shifted it into a genus of its own: Lamiastrum, which apparently means "sort of like Lamium." It has retained its former species name and is thus now Lamiastrum galeobdolon. Both lamiums and lamiastrums are members of the mint family [speaking of invasive plants], and are both sometimes referred to as "Deadnettle", for no good reason that I can see. None of these plants have spines, but they do have the faint odor of mint if crushed. There are several lamiastrum cultivars, including one known as Silver Archangel. The plants are extremely winter-hardy, to the point of being evergreen here in Zone 5.
As a groundcover or a container plant, Archangel has attractive foliage, like the lamiums - usually some variation of silver and green. The flowers are small and fairly insignificant, held on small spikes a couple of inches high. Unlike the lamiums, which are in the range of blue to pink, or white, the flowers of lamiastrums are bright yellow, which once gave them the name "Yellow Lamium".
Because of its invasive habit, L. galeobdolon has been listed as a Class C noxious weed in Washington state. It has typically spread into the wild as gardeners dump waste or send it for composting; when cutting back this plant, it should be disposed of as garbage rather than composted.
I may have finally rid myself of the Yellow Archangel, although the remedy was drastic. This winter a plumbing problem resulted in the arrival of a backhoe, digging up the entire bed. But I am now once again in search of a groundcover for a dry, shady area. I wonder if one of the true lamiums might be better-behaved than their yellow cousin.