Once in 18 years.

Under a sign on the museum trails, the trilliums are blooming.

Western trillium, Trillium ovatum var. ovatum

Trillium likes shady, wet forests, and riverbanks where its feet stay wet. At the Campbell River museum, the trillium patch is on a dry (comparatively) slope, just below the paved walkway, in semi-shade, an unexpected location. (There may be some underground irrigation.)

Young flowers of this variety (ovatum) are white, but with age they may turn pinkish or even purple. (I haven't seen any purple ones, though.) Zooming in on this one, I can see the merest hint of pink; it's still young.

I checked bloom times for the area; at the southern tip of the island, in Victoria, trillium flowers in late March to early April. And near here, halfway up the island, I found records in the third week of April. 250 kilometres: 2 weeks delay in bloom. I noticed this same time delay when I drove north last week; travelling north is like setting the calendar back.

Around a corner, on the sunny side of the museum, in an unlabelled patch, I found a couple of unusual trilliums:

Multi-petalled trillium 

These were slightly smaller than the others, but they have the characteristic trillium three-fold pattern: three leaves, three pointed sepals, three petals. But these have three inner petals, as well. I found a match in E-Flora; it was also found in Campbell River, in the forest.

Another interesting fact about western trillium -- it can take up to 18 years for a plant to become sexually mature (i.e. able to produce flowers). (From Metro Vancouver Regional Parks' Facebook page.

Just one more reason never to pick a trillium; it's the fruit of 18 years' work!