The very glossy, evergreen leaves of low-growing Goldthread (Coptis trifolia) are most attractive, but before you start thinking this may be the ideal shade-loving ground cover for your shady garden, be aware that this little cutie demands a cool, acidic organic soil, and is not suited for warm urban conditions. It grows in damp moss under conifers and it sometime covers very old, decaying stumps, to lovely effect. When I lived in Toronto, I became accustomed to seeing Goldthread in only the coldest and most organic spots. So I was delighted, and a bit surprised, to see Goldthread in a woods near Beaux Arbres, romping along the side of an old logging track, in partial sun no less, forming an extensive low ground cover, even weaving in and out among the grasses and hawkweeds and other weeds in the trackway, finding the ordinary leaf litter and needle duff sufficiently organic for it to thrive. It is worth remembering that, compared to almost any spot in southern Ontario, this old track has cool and acidic soil. Still, it showed what is possible in the Ottawa area, if the right conditions for Goldthread are present.
Goldthread blooms in early spring. The pretty white flowers, with a boss of white stamens, are very briefly open. The white petal-like parts are actually sepals, and the true petals are modified into yellow nectar cups. If you can catch its very brief flowering, it is worth giving the flowers of Goldthread a close look. I have not been able to find out much about Goldthread’s pollinators but those little cups, brimming with nectar, suggest it is an important food source for somebody.
The plant spreads by thin rhizomes, which are bright yellow, and give the plant its common name. An older botanical name is Coptis groenlandica, the reference to Greenland giving us a clue to its preference for cold places.
Goldthread is one of the little woodlanders I will have in small quantities this spring. Although indisputably native to the Ottawa area, it is so little adaptable to urban conditions, I find it difficult to guess what the demand for it may be. Away from the downtown heat island, in a very well shaded garden, it might be worth trying Goldthread in, say, a wooden trough filled with a specially prepared soil mix (lots of well-rotted needle duff), with other charming miniatures, such as Common Wood Sorrel, Creeping Snowberry, and Bunchberry.