The Sunflower Hill Chronicles, Part 9: Observations, Flowers, and Invasives
June 24, 2022
By Birgitta Jansen
The current of life with its many twists and turns has a way of interfering with our intentions and Time is an expert at sweeping away the days and weeks… Thus it has come about that this essay was mostly written towards the end of June but not finalized until nearly the end of summer. Now it’s Sunflower Hill Chronicles catch-up time.
June was a remarkable month. The vegetation along the trails was super-lush in every possible shade of vibrant green. One day I encountered two visitors from Edmonton who have been coming to Kimberley annually for nearly 40 years. They said they’d never seen it this lush.
And then the profusion of grasses! They’ve come in thick this year and many of them are waist-high. I must admit I don’t know anything about the world of grasses and sedges. I’ve had my hands full this spring learning all about the flowers and I still feel like I’ve just begun.
However, I have learned from Laura Duncan that that one species, collectively known as spear-grasses, has adapted to produce seeds that bury themselves in the ground by drilling into the soil. When a few of these seeds drill into boots and socks of hikers, they can be quite uncomfortable. The bigger issue is that they can cause serious damage to both wild and domestic animals when they drill into the animals’ fur and then into the skin. As Laura knows from experience, for pet owners, this sometimes results in a trip to the vet!
June temperatures started out rather cool with frequent overcast skies and some days it rained. One day this spring I walked The Hill in the clouds and fog, which I love. There is a sense of mystery and intimacy about a landscape shrouded in tiny droplets of mist. It is true; we’re all “sky-walkers.” The sky begins at our feet.
During the last two weeks in June, temperatures rose dramatically. Summer, long awaited, arrived seemingly overnight. A few of the snowbrush bushes (Ceanothus velutinus) exploded in a multitude of beautiful fragrant white blossoms. But many of the shrubs seemed to be struggling. Hard to tell why. Hungry ungulates during the winter? A late-ish summer?
The wild roses and blue lupines finally ventured forth into bloom but were not as prodigious as I’ve seen them other years. Especially the lupines were sparse and small. Each year seems to provide an optimum time for different species depending on weather, temperatures, rain, etc. There are so many factors involved and we really don’t understand them all. This year we saw happy three-spot Mariposa lilies (Calochortus apiculatus)and yarrow (Achillea millefolium) everywhere. Meanwhile the purple shrubby penstemons (Penstemon fructicosus) continued to go strong as well as the blue harebells (Campanula rotundifolia). Everything has its own cycle as to when it grows, blooms, and starts to fade.
There is one striking yellow flower that tends to rise above the crowd and is a real eye-catcher. It turns out to be the yellow salsify (Tragopogon dubius). Its seed head looks reminiscent of a dandelion gone to seed, but larger. This plant is of European descent and appears to have lived here for a while already. Apparently, many Indigenous peoples also cooked and ate the roots, which means it has been around for a while. This brings up the question of when a plant is considered invasive. Does it ever cease to be invasive and become an accepted part of the native plant population? This last one is an interesting question to which I could not find a satisfactory answer. It appears to depend on how much of a “nasty” the plant is.
Species are often brought into a region by accident or imported on purpose to be planted in gardens. Both ways of distribution seem to have increased as many more people travel more frequently and to widely different ecosystems. Often consequences are disregarded or simply not anticipated.
The common opinion appears to be that a species is considered invasive if it adapts and grows aggressively in wide variety of areas, has a high reproductive rate, lacks natural predators, and monopolizes resources to the detriment of the native species. It is destructive to the ecosystem in which the native plants have developed and thrive. Invasive species can be allelopathic, which means that they produce biochemicals that compromise the survival of native plants around them.
Climate change could also play a role in the increased appearance of invasive species. Lands disturbed by landslides, flooding, logging, road building, drought or fire stress the existing ecosystem and create openings for more opportunistic invasives to come in and spread. Many invasive species tend to appreciate disturbed areas.
One unwelcome invasive on Sunflower Hill is the purplish spotted knapweed (Centaurea maculosa), also brought in from Europe. Animals don’t eat it because it is not a very tasty snack. Much like many other invasives, knapweed releases a chemical (in this case: catechin) that prevents the germination of neighboring plants or inhibits root growth of other plants nearby.
Knapweed can be pollinated by pollinators but can also self-pollinate, and it is a prodigious seed producer. One plant can produce some 18,000 seeds. Once knapweed establishes itself, it takes over and pushes native plants out. It’s a really tough plant and can withstand drought and trampling, and it does just fine in rocky soil. Even if the seeds don’t germinate in the year following, they form a seedbank and remain viable in the soil for approximately eight years! These characteristics make knapweed extremely difficult to control. Needless to say, the sight of these plants on Sunflower Hill is not encouraging.
In an effort to control invasive species on Sunflower Hill, Kimberley Nature Park Society volunteers began to organize “knapweed pulls” around 2003. Some targeted pesticide applications were also used. Kent Goodwin commented that, “Our main focus has been knapweed, and the fact that the hillside isn’t covered with it may in part be due to our efforts.” He added another interesting factoid: “In the early years, we also pulled Dalmation toadflax (Linaria genistifolia ssp. Dalmatica) but as B.C. started to release imported weevils in the Kimberley area that targeted that plant, we opted to let them do their job.” Another major concern is the sulphur cinquefoil (Potentilla recta),which is already well established on The Hill and mixed in with native (Prairie) cinquefoil (Potentilla pensylvanica). That makes controlling this weed difficult.
Cheatgrass is another invasive that is a significant threat because it is spreading rapidly and outcompetes native grasses. It is happiest in wet winter conditions and hot, dry summers. It is an annual plant (compared to native grasses, which tend to be perennial), and it dries out earlier than native vegetation, which means that in many regions it’s dangerously ready for fire season. It ignites easily and causes rapid spread of fire. And after a fire? Cheatgrass happily invades any empty spaces it can find. As it turns out, it got its start in North America in the 1950s and is one of the most problematic invasive species we see here.
There is one thing that can definitely be said about Sunflower Hill: It is never, ever boring.
All photos by Birgitta.The images above are taken with a specialized macro lens, which means the flowers are shown larger than you see them along the trail. You can also click on the photo to enlarge the image to full screen.