By Art Guppy
Mt. Prevost is a very small mountain (786 m.) a few kilometres north of Duncan on Vancouver Island. In appearance it is nothing more than a large hill covered by coniferous forest except for patches of bare rock near the summit. Its top has two humps, which are much too gently rounded to be called peaks, though on the south side of the highest hump there is a formidable cliff.
In spite of its modest height, Mt. Prevost is the home of some remarkable plants. Moisture-carrying winds from the Pacific cross the island, and often even in summer their moisture condenses as clouds around Mt. Prevost’s humps. Close to the ground, a cloud can be a dense fog that covers vegetation with droplets of water almost as if it had been raining. During the generally rather dry summers of southeastern Vancouver Island, that small amount of extra water may be just what is needed by the unusual plants on the mountain.
The most distinctive plant on the mountain is a dwarf form of Erythronium grandiflorum (yellow glacier lily) which has evidently evolved for life in shallow soil on rocky windswept slopes. The flowers are a little smaller, but otherwise very like those one sees blooming by the thousands on mountain slopes in the Cascades and in much smaller numbers on Vancouver Island on the higher mountains such as Mt. Arrowsmith. In comparison with the flowers of the same species east of the Cascades in B.C. and Washington State, they are much smaller, are a paler yellow, and their anthers are pale cream, rather than the deep yellow or red of the anthers of their showier relatives. No doubt as an adaptation to their exposed habitat, their flower stems are quite short and seldom have more than one flower.
It is the leaves that make these little glacier lilies distinctive, for they tend to be very long and narrow, v-shaped in cross section, and held low against the ground — perfectly shaped for windswept slopes with such shallow soil there is little competition from larger plants. Here and there, one sees one of the lilies with wider, more erect leaves, telling us they still carry the genes of the more usual forms of the species which are adapted for life in mountain meadows among masses of competing plants. Here on Prevost, they generally have little competition except from mosses and scattered grasses.
Almost certainly this dwarf Erythronium is strictly endemic to the low mountains of southeastern Vancouver Island, but I am not sure how many of those mountains have it. I am sure I have seen the same thing on Mt. Benson, near Nanaimo, though it is not plentiful there. Years ago I saw numerous Erythronium grandiflorum on Green Mountain, near the Nanaimo River, but they had finished flowering and I didn’t inspect them closely as I had much to look at that day. It is a higher mountain than Prevost, and the conditions there were more like those of an alpine meadow, so the plants may have been a form adapted to those conditions. I would like to hear from anyone who has seen the dwarf form on other mountains.
In the spring of 2010 I visited the little glacier lilies on Prevost after not seeing them for several years, and I was shocked to see their numbers much depleted. Grazing by deer may be part of the problem, as the removal of wolves and cougars near cities tends to cause deer populations to become unnaturally large, and the animals are driven to feeding in a manner more like that of goats, which is destructive to low vegetation. It is a basic principle of nature — though one that some people would rather not think of — that predation by carnivores is essential to a healthy population of herbivores.
On Camas Hill, a steep, rocky hill where I used to live west of Victoria, the deer population grew until trilliums and Columbia lilies were almost entirely wiped out, and the Sedum spathulifolium, which is the food plant of the little Moss’s Elfin butterfly, was so depleted that the little elfins, which had been quite common in early spring, became quite rare. Driven by hunger, the deer even obliterated much of the licorice fern to the point where large patches of it remained only on the steepest rocks. Obviously in that area the lack of cougars and wolves was making life very difficult for deer.
Nevertheless, on Mt. Prevost I don’t believe it is deer that are the main cause of the depletion of the glacier lily population. I believe it is human feet. People are careful not to walk on the flowering plants, but when the Erythronium are not in bloom, their leaves are simply part of the vegetation which is pleasantly soft to walk on.
In the spring of 2010, after visiting the glacier lilies, I set off to check on another of the unusual plants, but as I trotted across the mountain hump, I had a sense of foreboding. What was I going to find? I had first come upon an unusual plant many years ago where it was growing on the very lip of the formidable cliff I mentioned above. At that time, there was a nice, healthy clump of what I immediately identified, from the very leafy stems and the chocolate colour of the flowers, as the northern riceroot, Fritillaria camschatcensis, but then I began to have second thoughts. That species normally is found in low moist places or at the top edge of a beach. The lip of a sheer cliff was totally wrong for it, but could suit the other chocolate lily, Fritillaria affinis, which normally has flowers of a paler brown liberally speckled with pale spots — not like any chocolate that I have ever eaten. I would need to come back later to see the seed capsules, as they would provide certain identification.
I did go back later, and found that a deer had eaten either the flowers or the capsules. Rather than be defeated, I dug my fingers into the soil above the bulb and obtained 3 or 4 of the rice-like bulblets that give the plant its name. In my garden those grains of “rice” took years to become sizable bulbs, but eventually there were flowers, and then seed capsules with high, narrow ridges or fins, which meant it was Fritillaria affinis, in spite of its dark chocolate flowers and leafy stems, which looked so much like they belonged to the other species. I came to suspect that the plant at the top edge of the cliff must be an F. affinis showing introgression from F. camschatcensis as a result of hybridization between the two species having taken place at some time in the past, though it would require a study of its DNA for positive identification. There are a number of plants of Fritillaria affinis on both humps of the mountain, but it would have required a very energetic pollinator to bring pollen of the other species from the rather distant moist places suitable for the other species. The only pollinator I have ever seen on the flowers of either of our fritillarias is a little fly rather like a common housefly in appearance, and it does not appear to be made for long-distance flying.
Nevertheless, I clung to the idea of introgression being possible, because in the past native people may have kept large areas on the mountain’s slopes free of trees as meadows where they could have collected camas bulbs as food, and in seepage areas in those meadows, there would have been the right habitat for Fritillaria camschatcensis.
The question of the true identity of the strange chocolate lily was very much on my mind in 2010 as I approached the top of the cliff, but mainly I simply wanted to be sure it was still safely on its cliff-top perch. I reached the spot, and there it was — at least, there was what was left of it. Most of the clump was gone. Only a stem with two or three flowers remained of the beautiful clump. This time deer were surely to blame. Anyone who had walked on the clump on its perilous perch would later have been scraped off the rocks at the foot of the cliff.
I was feeling disappointed and sad as I set off to see the third unusual plant on the mountain, but I was greatly cheered to find those plants in fine shape, and every bit as interesting and beautiful as I had ever seen them. These were not plants that could be easily trampled upon unless by extraordinarily athletic people, and I doubt they would tempt the appetite of a deer. This time, I was certainly dealing with hybrids, but the parents are so unlike each other, one would never think they could cross, but they do, and in a number of dry, rocky places near the coast. At several such places I have encountered the hybrids, but nowhere have I seen a better display of them than on Mt. Prevost.
One parent is the low, creeping, rock-hugging or ground-hugging plant known as kinnikinnick (Arctostaphylos uva-ursi), and the other parent is hairy manzanita (Arctostaphylos columbiana), a large shrub, sometimes almost tree-like with a twisted, gnarled trunk or trunks as much as 3 metres tall. Each of the parents can be beautiful, but in very different ways: kinnikinnick as a carpet of glossy green leaves with clusters of showy, pink, urn-shaped flowers, and hairy manzanita as an artistic creation of gnarled branches from a trunk clothed in reddish bark. The hybrid offspring of this odd couple can be almost anything you could imagine might be produced by the mixing of such different collections of genes. You’ll find many of those strange children on Mt. Prevost, especially on the east hump. The flowers can be anything from the white that is usual for the almost tree-like parent to the bright pink of the best plants of kinnikinnick. As to size and posture, take your pick; they are all there.
As I finish writing this piece, I can look to my left out the window that frames my view of Mt. Prevost. It is early evening and the sky is pale blue flecked by clouds with touches of grey and pink. I am very fond of that mountain.