Thanksgiving Sunday morning, Jacques Cayouette, a senior botanist for Agriculture Canada – Biodiversity division, and some of his colleagues, came to Beaux Arbres on a quest for rare ferns. They were interested in our farm’s infertile and abandoned pastures as likely sites for Botrychium (now called Sceptridium) ferns.
The pastures on the farm were abandoned more than sixty years ago. Sumacs and raspberries are creeping in, followed by black cherry and white pine, at the edges nearest to remnant woods, but most of the pastures remain open. The sandy soil is so dry and infertile that lichens dominate and the old field plants – common milkweed and goldenrod, black-eyed Susans and tower mustard – struggle.
I had invited a few botanically minded friends from the Pontiac, and we joined Jacques’ group as they spread out over the nearest old pasture. They soon found two species: Grape Fern (Sceptridium dissectum) and Leathery Grape Fern (S. multifidum). They are small ferns, a few inches high, with one green frond and one upright fertile frond each. These are the two commoner species. We were able to find quite a number of each, which allowed us to get a good feel for the considerable variation found within each species.
Feeling chuffed, the professional botanists kept their keen eyes focussed for grape fern. The prize was St. Lawrence Grape Fern (S. rugulosum), a genuine rarity that only grows in open sites on fine sands in the Great Lakes/St. Lawrence area. Eureka! The botanists found some specimens they were quite sure were the rare St. Lawrence Grape Fern. Jacques bagged a specimen to take back to the lab for confirmation.
Given the variation within the species, especially within S. dissectum, and the rather subtle differences between the species, I am not at all sure I have a good feel for what marks a plant as St. Lawrence Grape Fern. It is more rugulose than the other two. Okay. I think I have it. I will have opportunities to revisit our fern site – hey, its just beyond our farm pond – this fall. The grape ferns have an unusual growth cycle. The fronds emerge in late summer – St. Lawrence Grape Fern emerges later than the other two – and last into the winter.
I am very grateful to Jacques for showing me the ferns I would otherwise have overlooked. I used to think the old pastures were not that botanically interesting as they seemed highly disturbed and dominated by common early succession species. I thought the lovely lichens in the lichen crusts were the most interesting thing about them. Now I know that what might well be the rarest species we have on the farm is there in the old sandy pastures.