I had a bit of a laugh of disbelief when I learned the common name for this species: small-flowered mitrewort. The reason? The first species of mitrewort I ever became familiar with, the boreal Mitella nuda, has flowers that are perhaps a quarter the size of these – far more deserving of the adjective!
The genus Mitella contains a dozen species or so, distributed in temperate to arctic North America and eastern Asia. The states of Washington and Oregon are the centre of diversity, with eight species occurring in Washington and one fewer in Oregon (see Mitella of Columbia River Gorge for photographs of five other species). Mitella stauropetala is divided into two varieties, variety stauropetala (meaning cross-petaled) found in Washington, Oregon, Idaho and Montana and variety stenopetala (meaning narrow-petaled) found in Idaho, Wyoming, Utah and Colorado. Considering today’s photograph was taken within a stone’s throw of the Washington-Idaho border, it is safe to say this is variety stauropetala; photographs are generally lacking online for comparison of the two varieties (for example, the Burke Museum, which is usually an excellent source of Washington native plant images, only has one for Mitella stauropetala var. stauropetala).
Greya moths have a mutualistic relationship with the Saxifragaceae, akin to the relationship between yucca moths and Yucca plants. Not surprising perhaps – Greya and Tegeticula (the major genus of the yucca moths) are both in the family Prodoxidae. Mitella stauropetala is used by Greya mitellae as a host plant. The adult female moths lay their eggs in the flowering scapes of the Mitella, and the larvae subsequently feed on the developing seeds. As a benefit to the plant, the moth acts as a pollinator.