The flowers typically have multiple showy stamens but no petals.
“Surprise is the greatest gift which life can grant us” is a quote attributed to Russian poet and novelist Boris Pasternak, and I can only assume the great writer was referring to surprises of the pleasant variety. For me, the Arboretum—with its staggering diversity of plant species—is a constant source of happy surprise and wonderment, a gift that keeps on giving.
For example, late last spring I was strolling through the Cascadia Forest at the south end of the Arboretum and—next to the main trail by the garden’s circular stone bench—I caught sight of some flowers I’d never seen before. They sat atop a short shrub that looked very similar—in form and foliage—to our native ocean spray (Holodiscus discolor), which is planted en masse in that area. However, the blooms on this mystery plant were quite distinct: In place of the ocean sprays’ wonderful white-cap-like, drooping flower clusters were adorable, white, cotton-ball-like inflorescences.
I could not find a tag on the plant, so I immediately emailed a photo of it to our Curator of Living Collections, Ray Larson, who cleared up the mystery: “That is Neviusia cliftonii, sometimes called Shasta snow-wreath.”
“What a great name!” I thought at the time, and I also knew right away that we’d be featuring this plant in our next spring issue of the “Bulletin.”
A Recently-Discovered Rare Beauty
Every year, scientists discover about two thousand new species of plants around the world. While news of these discoveries generates awe and excitement, it often comes with a caveat that many of these hitherto-unknown plants already face the threat of extinction.
Not surprisingly, a lot of the new species are discovered in remote tropical rainforests and cloud forests. However, some are found much closer to home—including, as it turns out, the Shasta snow-wreath. A medium-sized deciduous shrub endemic to Shasta County in northern California, it was only discovered by botanists in 1992 and is limited to around 20 small populations in the mountain forests surrounding Lake Shasta.
This “lake” is actually a reservoir and popular recreation area about 10 miles north of the town of Redding. It was created in the late 1940s as a result of the impounding of the Sacramento River by the Shasta Dam. We now know that the dam construction flooded—at least partially—six of the snow-wreath’s remaining populations.
One of the four specimens growing in the Arboretum’s Cascadia Forest.
“Snowfall” in Springtime
An erect, multi-stemmed shrub, Shasta snow-wreath grows up to eight feet tall and produces oval, coarsely toothed green leaves. When not in flower, it not only resembles ocean spray but also another very common native shrub, Pacific ninebark (Physocarpus capitatus)—which may explain why the species eluded the attention of botanists for so long.
Though Shasta snow-wreath is a member of the rose family, Roseaceae, its stunning flowers don’t resemble those of its rose, apple or cherry cousins. One crucial difference is that they usually don’t have any petals, and what you see are thick clusters of white stamens (about 50 per inflorescence), the male fertilizing organs. This gives them the appearance of white puff balls—hence, the plant’s snow-themed common name.
The flowers bloom in spring (around late April to early May in Seattle). Five greenish, leaf-like bracts can be found at the base of the explosion of stamens, but they are rather inconspicuous—as are the small, dry, brownish seed-like fruits (technically “achenes”) that develop from the flowers.
A Tiny Genus
The genus Neviusia contains just two species, and Shasta snow-wreath’s closest relative lives all the way in the opposite, southeast corner of the United States. Alabama snow-wreath, Neviusia alabamensis, looks similar to Shasta snow-wreath, though it is generally shorter and more arching in habit—and has even more stamens in each flower (100-plus). Though its range covers several states in the Southeast, the populations are small and scattered, and the species has also become one of conservation concern.
The genus is named after Reuben Denton Nevius (1827–1913), a reverend and amateur botanist who discovered Alabama snow-wreath in 1857, while on a hike near Tuscaloosa. At one time, the genus had a much wider distribution. For example, fossils of an extinct species, Neviusia dunthornei, have been found in the 50-million-year-old shale deposits of the Okanagan Highlands of Washington state and British Columbia.
Shasta snow-wreath blooms in April and May in Seattle.
In the Arboretum and Beyond
As part of its Conservation Collection, the Arboretum has four specimens of Shasta snow-wreath growing in the Cascadia Forest, all of them along the trail next to the large, circular stone bench. Three date to 2015 and were sourced from the MsK Nursery at the Kruckeberg Garden in Shoreline. The fourth dates to 2018 and was gifted to us by botanist Dick Olmstead, a professor emeritus in the University of Washington Department of Biology.
Ray says that Dick’s specimen also came from the MsK Nursery. I contacted the Kruckeberg Garden, and their horticulturist Vicki Demetre informed me that, in their historical documentation, Art Kruckeberg noted that their specimen came from a cutting taken from a plant at UC Botanical Garden, Berkeley, California in 2000.
The Arboretum also has a much older grouping of the Alabama snow-wreath, growing on the north slope of the Woodland Garden. These plants were donated in 1948 by Donald Graham, a founder of the Arboretum Foundation. In cultivation, snow-wreaths perform best in moist, well-drained soils in partial shade or full sun. In the wild, they are typically found on limestone soils, however they seem to adapt well enough to more neutral or acidic substrates, which are more common in gardens here.
Both Neviusia species are difficult to find at nurseries, though some online sources are available. Vicki at the Kruckeberg Garden says that they occasionally propagate Shasta snow-wreath in small batches from cuttings of their specimen and sell them in the nursery. Whether you have a home garden or not, you can always visit the Arboretum or the Kruckeberg in April/May to see some beautiful springtime “snow.”
Niall Dunne is the “Bulletin” editor and the communications manager at the Arboretum Foundation.
References
- Cameron, R. (2025) “Neviusia,” from the International Dendrology Society website “Trees and Shrubs Online.”
- Nelson, J.K. “Plant of the Week: Shasta snow-wreath (Neviusia cliftonii).” U.S. Forest Service.
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This article is reprinted from the spring 2026 issue of the Arboretum Bulletin, our quarterly botanical and horticultural magazine. Published since 1937, the Bulletin is a benefit of Arboretum Foundation membership and features in-depth articles on the Arboretum collections and history, as well as general information of interest to plant lovers in the Pacific Northwest and beyond. Join/subscribe today.
