The 25 ha Purdon Conservation Area includes a mixture of wetlands (shallow water, shoreline marsh, and fen) as well as some upland forest. The fen consists of both open and treed fen, with the open fen having a particularly significant display of unusual plants. One of the most noteworthy plants is a large population of Showy Lady’s-slipper (Cypripedium reginae), a species of wild orchid. The best time to visit to see these in flower is around June 12 to 25. Later in the year, there are flowing populations of Bog Goldenrod (Solidago uliginosa) and Shrubby Cinquefoil (Potententilla fruticosa). Both these species have conspicuous yellow flowers. The Purdon Fen has a boardwalk which allows visitors to see the different kinds of habitats and fen species without damaging the wetland.
This table lists all the significant plants found at the fen, with their status in Lanark County.
A fen is a specific kind of wetland, one that has a shallow layer of peat and continuous movement of ground water. In many cases, fens turn into bogs as the layer of peat deepens. Often this is accompanied by a change from open herbaceous vegetation dominated by sedges, to woody plants. In the case of the Purdon Fen, the common tree species is White Cedar (Thuja occidentalis).
There is active management of conditions at the Purdon Fen, with occasional removal of White Cedar trees to maintain the open fen conditions. This provides the necessary sunny habitat for species such as Showy Lady’s-slipper.
To learn more about the Purdon Fen, you can consult the following sources:
Read David White’s description of the Purdon Fen in Trail & Landscape. (This is the source of most of the above information. )
To learn more about calcareous fens in eastern Ontario, you can read Reddoch, J. 1979. Calcareous fens in the Ottawa District. Trail and Landscape 13(1): 16-27.
For a good general introduction to this type of habitat read this description of Northern Fens prepared by the Michigan Natural Features Inventory.
If you are curious about the how fens and bogs differ from other wetlands, you can read the first chapter of Paul Keddy’s book, Wetland Ecology.
Paul Keddy, Ph.D. 