Plant of the Week: Douglas Aster

Image source: https://www.flickr.com/photos/12567713@N00/2809146063

This entry is from Lucas Costner, an undergraduate horticulture major at Oregon State University.  It highlights one of the plants that Aaron Anderson is using in his research.

A common and much-beloved Northwest native, the Douglas aster, happens to be a bit of a misnomer. This profusely blooming, purple-flowered perennial isn’t a member of the Old World Aster genus, but rather belongs to the New World Symphyotrichum (2). As such, our Douglas aster (Symphyotrichum subspicatum) is closely related to its East Coast look-alike, the New England aster (Symphyotrichum novae-angliae), and evidence suggests the two descend from a common ancestor (2).

Naming conventions aside, the Douglas aster should be noted for offering an impressive, season-long (July – September) display of attractive, disk-shaped, and papery flowers while asking for little in return. Like many of the other native plants I have written about to this date, this plant is incredibly hardy and will spread via creeping rhizomes if given the opportunity (3). The USDA Natural Resources Conservation Service recognizes the Douglas aster as being abundant and present from Alaska to California, and into Idaho and Montana (1). In the wild, it is noted as being found in forests, along the banks of streams, and even along the coast (3).

In Oregon gardens, west of the Cascades, the Douglas aster will again require little in terms of care once established. It does prefer full-sun, and well-drained soil, but it similarly thrives in wetland areas (4). Our test subjects in the field faced many hardships, ranging from drought to over-zealous mowing, and still ended up thriving. Therefore, as with the majority of the native plants written about here, this plant may not be appropriate for every garden or indeed for every gardener. The most exciting part about the Douglas aster, however, is not its robust growth habit; but rather, its potential to benefit wildlife and therefore our suburban and urban environments.

In the field, other members of the Asteraceae family (think goldenrod and pearly everlasting) have anecdotally been some of the most popular plants in terms of pollinating visitors, and our Douglas aster plots were no exception. At times, it was hard to keep track of just which insects had or had not been counted during our five minute observations due to their sheer abundance. Thanks to the long bloom period, it was also exciting to the see the progression of pollinators develop as the season passed week by week, and the species composition gradually changed. While the Douglas aster is noted for its attractiveness to many species of butterflies, our observations could suggest that is similarly attractive to a fairly wide array of bees as well (4).

Sources:

1. “Plant Profile for Symphyotrichum subspicatum subspicatum (Douglas aster).” Plants Database, USDA NRCS, plants.usda.gov/core/profile?symbol=SYSUS.
2. Candeias, Matt. “How North America Lost Its Asters.” In Defense of Plants, 12 Oct. 2016, www.indefenseofplants.com/blog/2016/10/12/how-north-america-lost-its-asters.
3. Knoke, Don, and David Giblin. “Symphyotrichum subspicatum.” WTU Herbarium Image Collection, Burke Museum of Natural History and Culture, biology.burke.washington.edu/herbarium/imagecollection.php?Genus=Symphyotrichum&Species=subspicatum.
4. “Douglas Aster.” Washington Native Plant Society: Starflower Image Herbarium, 5 Nov. 2007, www.wnps.org/landscaping/herbarium/pages/aster-subspicatus.html.