Pacific Northwest Native Plant Profile: White spiraea (Spiraea betulifolia var. lucida)

Spiraea betulifolia var. lucida

Even though it’s growing and thriving in my front yard, it took an October trip to northeast Oregon’s Wallowa Mountains to remind me why I love white spiraea (AKA shiny-leaf spiraea or birch-leaf spiraea), or botanically speaking, Spiraea betulifolia var. lucida. In Latin, lucida means “bright,” or “to shine,” and shine it does.

Uncommon, small (as shrubs go, to about 3 feet tall), erect and deciduous, it’s a very attractive native plant that spreads slowly by rhizomes. Though its seeds are also perfectly capable of reproducing and may be distributed by birds, rodents, or wind, I find it’s not a strong self-sower.

Besides its small stature that allows it to fit into tight spots, it has many other attributes and I can’t imagine why it’s not planted more often in yards and gardens. It’s barely mentioned in my book, so here I give it its due.

In late spring to early summer, creamy white flowers—sometimes with a pale pink blush—show up in flat-topped clusters, from 2 to 5 inches wide. With occasional deep summer watering, it will sometimes bloom during late summer and even autumn. And as the flowers mature they offer lovely, although fairly inconspicuous, golden brown seed heads that continue to captivate.

Spiraea betulifolia var. lucidaBut the best is yet to come: Fall may be its prime season when its oval to oblong toothed leaves turn lovely shades of gold, orange, red, and burgundy. The entire little shrub lights up like a flame above the dark, moist soil and fallen leaves beneath it.

 

How it grows
White spiraea naturally occurs in parts of western Canada, Washington and Oregon, and as far east as Minnesota. It grows along streams and lakes, in mountain grasslands and on the slopes of forests (especially rocky ones) both east and west of the Cascades, from sea level up to about 4,000 feet, although it can be found at higher elevations in moist forests. Since it’s best to grow native plants that are indigenous to your area, find out whether it occurs naturally in your county with this USDA map.

Last week I was pleasantly surprised to find it in the Wallowa-Whitman National Forest along the Wallowa Lake Trail and the Hurricane Creek Trail near Joseph, Oregon, in forested areas. Since these areas can get quite dry in summer, the plant’s drought tolerance is likely due to its rhizomatous ways. Often surviving in burned areas, fire kills the aboveground part of the plant, but it resprouts from “surviving root crowns, and from rhizomes positioned 2 to 5 inches (5-13 cm) below the soil surface,” according to the US Forest Service. Along the Hurricane Creek Trail, which meanders through a burned area, white spiraea was joined by “pioneer” species like western yarrow (Achillea millefolium var. occidentalis), and western pearly everlasting (Anaphalis margaritacea).

Wildlife value
The flowers—often with an extended bloom time—offer pollen and/or nectar for pollinators such as native bees, syrphid (flower) flies, butterflies, wasps, and ants. Leaves and branches offer a bit of cover for small creatures, and fallen leaves protect the soil and overwintering invertebrates, which provide food for myriad other species. It’s reportedly rather unpalatable to mule deer and elk, for those of you wanting native plants that won’t disappear overnight.

Try it at home
White spiraea is a fantastic little shrub that can be used in the places that a large shrub would outgrow in a few years. It’s also quite versatile when it comes to both light and moisture conditions. It can handle quite a bit of shade to a fair amount of sun, but seems to do best in part shade. A restoration project in Montana found that the plants did much better on east or south-facing slopes, rather than west-facing slopes with hot afternoon sun. At the Portland community garden where I have a plot for growing veggies, white spiraea was planted (before I acquired my plot) in native beds that border the garden. The beds provide a little test because the sunlight that reaches them varies from just a few morning rays to about a half day of sun to nearly all-day sun. Echoing the Montana study, the spiraeas that thrive are in the partly shaded area; many of the ones planted in a narrow sunny strip along a hot concrete walkway died due to heat and drought, while those that remain in that strip just barely hang on despite my best efforts with extra water and compost. The plants in full shade survive, but don’t look their best or flower much.

Spiraea betulifolia var. lucida

Plant them about 3 feet apart and at least 3 feet from walkways, since they will eventually spread and you don’t want to be constantly pruning them back. Amending soil with some organic matter (like compost) will help them get established, although they are quite tolerant of clay soil, and they do well with rocky soil. Mulch them with a natural mulch (like leaves) and keep them well watered the first 2 to 3 years, after which they should be quite drought tolerant (unless you have them in hot afternoon sun, which I don’t advise!).

Grab a partner
Grow white spiraea with associated species that also naturally occurred in your area, to help provide an eco-functional space for wildlife. It naturally occurs within Douglas-fir, grand fir, ponderosa pine, and lodgepole pine communities. Though shrubs and perennials in those communities are far too numerous to list here, consider serviceberry (Amelanchier alnifolia), red-twig dogwood (Cornus sericea), blue elderberry (Sambucus nigra ssp. caerulea), and Cascade Oregon grape (Mahonia nervosa). As always, buy plants that come from locally-sourced material at reputable nurseries.

 

© 2016 Eileen M. Stark

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