Orchids

Among the most diverse (about 30 000 species worldwide), specialized, and flamboyant families of flowering plants, orchids are widely distributed and are found in all parts of the world, except in the major deserts. While their attractiveness has prompted much horticultural interest, relatively few botanists have conducted serious research on the family. Thus, much remains to be discovered about these mysterious organisms that constitute one of the most striking and successful streams of plant evolution.

Three basic types of orchid are recognized: epiphytic, terrestrial, and saprophytic. Epiphytic orchids encompass most of the tropical and subtropical species — these are the “aerial” plants that attach to, and suspend themselves from, tree trunks, branches, and rock faces. Terrestrial species are typically anchored to the ground via underground roots with which they obtain nutrients. Saprophytic orchids also have underground roots, but they lack chlorophyll, their leaves being generally small and yellowish, and have lost the power to photosynthesize. Saprophytic species, like the widely-distributed Spotted Coral-root, secure nourishment directly from decaying organic matter in the soil.

Regardless of type, most orchids are notable for their ability to produce prodigious numbers of seed; a single capsule can contain up to ten million. Interestingly, after dispersal, the seeds of many orchids cannot germinate without infestation of a suitable mycorrhizal fungus. Once germinated, the path to a flowering orchid is barely begun; many species may take up to 10 years or more to mature. A long trajectory to reproductive maturity means that many species are found only in habitats that are at least moderately stable. Long maturation time and the fact that soil conditions must be “just right” for fungal infection and seed germination suggest that many orchids can serve as valuable indicators of environmental change.

While the majority of the world’s orchid species are tropical and subtropical in distribution, 77 species can be found within Canada. At least four of these have 70% or more of their North American range in Canada. In fact, the range of several orchid species, such as Spotted Lady’s-slipper, Sparrow’s-egg Lady’s-slipper, and Northern Twayblade, is largely restricted to cooler regions of Canada (and Alaska). These three species all occur north of the Arctic Circle, and Spotted Lady’s-slipper, a true northerner, can be found in North America only in the Northwest Territories, Yukon, and Alaska.

Orchids are associated with many different types of natural communities in Canada, including bogs, meadows, fields, swamps, fens, prairies, and forests. Given the sweeping breadth of Canada’s boreal forest region, stretching from Newfoundland in the east to Yukon and British Columbia in the west, it is not surprising that many orchid species associated with boreal spruce forests and peatlands have a widespread distribution in Canada. Similarly, species restricted to only one province are often associated with narrow floral regions. For example, Nodding Pogonia is found only in the very restricted Carolinian region of Ontario. Some orchid species tend to be more liberal in their habitat requirements, occupying different types of habitats in different geographic regions. Blunt-leaf Orchid, for example, is found all the way from the Arctic tundra region in the north down to the northern edge of the Carolinian region in the south.