This particular species of false lily-of-the-valley or snakeberry has a distribution range that borders the north temperate Pacific Ocean. In Asia, it is found in Japan and the Kamchatka Peninsula. Its North American distribution stretches from Alaska south to northern California. Generally, in North America, it is found west of the Coast-Cascade Mountains, though it does stretch east along the British Columbia and Washington border, and even has a disjunct population in northern Idaho (distribution map in NA).
I was intrigued by the colonization of the tree trunk by these plants. Or plant–it could be one genetic individual, given that the Flora of North America describes Maianthemum dilatatum with the character of: “Rhizomes sympodial, proliferatively branching.”. The rhizome is a creeping stem; sympodial means that individual plant forms many lateral shoots to expand outwards along the edges of the clump instead of growing only from the terminal point of the stem (i.e., forming a runner). This strategy of growth helps make Maianthemum dilatatum a desirable shady-spot groundcover.
These photographs are from mid-June in 2007.