My copy of the thick garden reference, The American Horticultural Society A-Z Encyclopedia of Garden Plants, has a full page devoted to Crataegus, the hawthorns. I’ve been thinking quite a bit about narrowly endemic northwestern species lately. None of those are in the Encyclopedia, but the book does include several eastern North American species.
Here in the Pacific Northwest about the only hawthorns I see in home landscapes are varieties of Crataegus monogyna, singleseed hawthorn, and C. laevigata, English hawthorn. Both of these are introduced to North America from Europe. In May they’re covered with blossoms, white or in some cultivars, red. Later in the season they produce prodigious quantities of red berries. Birds dine on the berries and deposit seeds out in the woods. You know what happens next: non-native hawthorns springing up all over the place. That’s where the flowers above were photographed: a garden escapee along a trail near Whatcom Creek in Bellingham, Washington.
Why do gardeners and landscapers continue to plant non-native, European hawthorns when we have so many native selections?
North America is home to a huge number of hawthorns. There are eight northwest species I’m photographing for an upcoming field guide due out in 2014. My copy of Flora of West Virginia, my home state, includes 37 species in the key. The USDA Plants database returns over 220 species, with one or more native to every state and province.
The taxonomic “lumpers” have apparently been at work in the last 40 years, as the 1971 Flora of West Virginia stated, “This is a genus of unusual taxonomic difficulty, with more than 1,100 described ‘species’ in North American, by far the greater portion of these having their ‘ranges’ in the eastern United States.” In Washington state there are a couple of narrow endemic species that are fairly recently described. They’re limited to a small part of Okanogan County, just south of the Canadian border, along the Okanogan River. The same riverbanks also have our more common native species as well as some introduced ones.
Hawthorns can be difficult to distinguish from one another, although they’re relatively easy to identify at the genus level. Crataegus is a member of the rose family. They’re small trees or shrubs with simple, alternate leaves that can be either entire or divided. Flowers have five petals and 5-25 stamens, 5 styles, and blossoms in clusters (corymbs) at the branch tips or leaf axils. Most have thorns. Fruits are small pomes (apple-like) with one to five bony nutlets. Some hawthorn species form almost impenetrable thickets while others grow more solitary.
The widespread and common hawthorn in the Pacific Northwest is Douglas’ hawthorn, also known as black hawthorn. It typically blooms in May, so should be coming into flower soon. It can form thickets or grow as a solitary specimen up to about 20 feet tall. Branches have sharp thorns about an inch long. The leaves are dark green above, lighter below, sometimes hairy, edges toothed with several short lobes at the tip, veins not extending to leaf edge between lobes. Flowers have 10 stamens (number of stamens is important when keying hawthorns). Fruit, which ripens in late summer, is dark blue-purple, almost black. The fruit is edible, although I haven’t tried them and J.E. Underhill in Northwestern Wild Berries says “The flavor of the ripe fruit is rather bland, slightly sweet, and a bit ‘dry and puckery’. Native Indians once used it, but it finds little favour today.” Other sources I’ve found describe the fruits as tasty and good in pies and jams.
Different species of native hawthorn are going to have different cultural requirements and hardiness. Look for the ones native to your immediate area for the best choices to plant in your garden.
In the northwest, Crataegus douglasii grows best in full sun. It tolerates wet feet in the winter and soils that dry out in the summer. It’s pretty resistant to diseases, although somewhat susceptible to a rust that has junipers as the alternate host. Hawthorns provide both food and cover for wildlife. The dense, thorny thickets with numerous branches make good resting and hiding places for birds. Birds, deer, and other mammals all consume the fruit in autumn and through the winter. More details on a US Forest Service web page for the species.
The Wild Garden: Hansen’s Northwest Native Plants has a page with much information about Douglas’ hawthorn.
I’ve photographed many northwest hawthorns, which you can see on my Pacific Northwest Wildflowers website. I’ll be looking for the rest of them, and for flowers on the ones I only have in fruit, this year.
It pains me when I go for a walk in some of our wooded parks and see non-native hawthorns growing along the trails. Our native species have so much greater value that I have to wonder why the others were originally planted. Probably something to do with trying to reproduce an English gardening experience wherever settlers landed. Fortunately, many gardeners are coming around to greater appreciation of our natives.
Go find yourself a native hawthorn and add it to your wildlife garden.
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