Yesterday I returned for visit number four to the site I’m surveying for the City. Historically the site was a landfill for a nearby brickworks, and took the ash and brick waste from the industry. The brickworks, and therefore the landfill, were shut down in the mid-1980s. The landfill was capped and covered with clean fill, and allowed to naturalize. These days the only remainder of the site’s prior use is an old shed at the far end of the meadow, tucked into the trees at the base of the ravine slope.
Of course, the legacy of the site also lives on in the vegetation found there. Being essentially one very large disturbed site at the time it was capped some 20+ years ago, early successional, fast-growing, and introduced species are all prominent through the central open area. The surrounding slopes are predominantly mature natural forest, but through the meadow the trees consist mostly of sumac, Manitoba Maple, poplars, and young pines. The site has been part of a tree planting program the City runs, and I gather the goal is eventually to reforest the site. Interestingly, I notice a lot of the trees they’ve planted aren’t in fact forest trees, but rather shrubby stuff such as hawthorn.
Along with the highly invasive garlic mustard that just seems to get everywhere, one of the common plants at the site is this lovely pinkish-mauve wildflower. It’s fairly common, I see it a lot in open fields, roadsides, abandoned properties, and re-naturalizing areas such as here. I didn’t really know what it was, but noting its resemblance to the phlox in my mom’s garden, I just labeled it a wild phlox.
In fact, it’s not a phlox, but this is a fairly common mistake. This is Dame’s Rocket, Hesperis matronalis, a native of Eurasia. Like so many of our introduced wildflowers, this species is a member of the mustard family, Brassicaceae. The easiest way to tell it apart from native phlox is by the number of petals: Dame’s Rocket has four (like all of the mustards), while native phlox has five.
The plants are prolific seed-producers, and seeds are quite hardy. The plants spring up earlier in the spring than many native meadow wildflowers, which tend to bloom in the height of summer. As such, it’s not uncommon to see extensive stands of Dame’s Rocket in meadow areas. Seeds of the plant are often included in wildflower seed packages, which aids in its spread. They prefer full sun or partial shade, but can sometimes be found in open woods as well. The flowering stems are likely two-year-old plants; most plants produce only a basal rosette in their first year.
There’s quite a variety of colour in a stand of the flower. It can vary from a deep pinkish-mauve to nearly white, with a full range in between. A few have variegated patterns on the petals. I’m not sure if this is a natural variation, or a result of gradual domestication. The flower was cultivated as a common garden plant in its native Eurasia, and brought over to North America in the 17th century for that purpose. These days it’s found scattered virtually across the continent, with the exception of the deserts and mangroves of the south, and most of the arctic tundra of the north.
Even though it’s introduced, Dame’s Rocket does have good benefits for wildlife. It’s frequently visited by many insects such as bees and butterflies for its nectar. Seed-eating birds will eat its seeds in the fall. Even in North America there are insects whose larvae will feed on the foliage, one of the most common being the Cabbage White butterfly. I’m not sure that placing the bird house in the middle of the stand of flowers really offers the residents any benefits, but it does afford them a nice view.
The genus name for Dame’s Rocket, Hesperis, is Greek for “evening”. The flowers of members of this group have very strong scents, which becomes much more noticeable in the evening. This strong fragrance also provides a couple of the other common names for the species: Night Scented Gilliflower, Summer Lilac, and Mother-of-the-Evening (the latter seems to imply that mothers are especially fragrant). Two other often-used names are Dame’s Violet and Sweet Rocket. I’m rather partial to “Gilliflower” myself, though.
I seem to be featuring a lot of introduced species here. Eventually I’ll find a native one! The more I look, the more I’m amazed at how many introduced species there are. I’d be interested to know what percentage of the wildflowers we see are actually introduced, both as a proportion of species, but also a proportion of biomass. I wonder if you can find that information somewhere…