Orchids of Algonquin Provincial Park

Orchids (Orchidaceae) are a particularly enchanting group of plants that delight many botanists. There are over 60 species that inhabit Ontario, 36 of which can be found in Algonquin Provincial Park, located in Central Ontario. Algonquin Park is home to a variety of different habitats, which helps explain its orchid diversity. 

While I am not nearly as orchid obsessed as some, I do enjoy seeing these beautiful and unique wildflowers, so I have made it a point of seeking out the species that occur in Algonquin Park. I have only managed to see a little over half of them within the park boundaries, and have seen several more of the species elsewhere. In this post, I will attempt to highlight and provide a brief overview the species that can be found in the Park, in alphabetic order as they appear in the Checklist of Vascular Plants of Algonquin Provincial Park (2020) by Sean Blaney et al. I will make reference to the West and East Sides of Algonquin Park in this post. The West Side is higher in elevation, comprised mostly of upland sugar maple-beech forests on glacial till. The East Side is lower in elevation, comprised largely of pine forests on sandy glacial deposits. Of course, there is some overlap in the habitat types.   

Dragon's-mouth (Arethusa bulbosa) is a particularly charming little species of orchid that hits peak bloom in late May into early June. This is a rather rare species in Algonquin Park, with most of the records coming from the Park's East Side. Despite it's apparent rarity, it is likely widespread, albeit in low densities, and just under detected. It is often found growing on bog mats. 

Dragon's-mouth (Arethusa bulbosa)

Sort of looks like a dragon!

I'm not entirely sure what the mechanisms are behind the species' distribution in the Park. The above individuals were photographed in a location with some unique associates, Meagre Sedge (Carex exilis) and Buckbean (Menyanthes trifoliata). 

Tuberous Grass Pink (Calopogon tuberosus) is a fairly familiar orchid to those who many find themselves in a bog during early summer. This orchid is special in that its flowers are upside down. It is not particularly common in Algonquin Park, but is widespread. 

Tuberous Grass Pink (Calopogon tuberosus)

Frog Orchid (Coeloglossum viride) is not common anywhere in Ontario, and is considered rare in Algonquin Park. The only record(s) are from the West Side. I have not seen this species in the Park.

The coralroots are always fun. By far the most abundant is Spotted Coralroot (Corallorhiza maculata), and both the western (var. occidentalis) and eastern (var. maculata) varieties can be found. Early Coralroot (Corallorhiza trifida) and Striped Coralroot (Corallorhiza striata) are also known, but are not as commonly encountered. The latter is rare and only known from the East Side. Coralroots are well known to be mycoheterotrophic orchids. 

Spotted Coralroot (C. maculata var. maculata)

Spotted Coralroot (C. maculata var. maculata)

Probably the most well known of Algonquin's orchids are the lady's-slippers. Only one, Pink Lady's-slipper (Cypripedium acaule) is common. You are more than likely than not to encounter this species somewhere in your travels during June and early July in the Park. 

Pink Lady's Slipper (C. acuale) (London, ON)

Ram's-head Lady's-slipper (Cypripedium arietinum) also had records from Algonquin Park, on the East Side. The last record was in 1982. Last June I embarked on a backcountry journey to check out where they were last seen, but came up empty. I thought for sure that they must be extirpated...that was until late August. No, I did not find Ram's-head, but I did have a conversation with Dan Brunton over a lunch break during a day of botanizing. He indicated that the area I had checked for the species was, although suitable, not where the records had come from. So maybe we shouldn't say the population is gone just yet. That being said, this species is particularly sensitive to disturbance, and is apt to disappear, so the optimism may be in vain. Perhaps this will be a goal of 2023. 

The only non-native species of orchid in Algonquin Park, and one of very few in Ontario, is Broad-leaved Helleborine (Epipactis helleborine). In Algonquin, it is most often seen in areas of human disturbance, although it was growing was commonly along the Bonnechere River floodplain last Summer (not directly beside development, although quite close). It is increasing in abundance, although I don't think necessarily poses a risk to native flora.

Broad-leaved Helleborine (E. helleborine)

The rattlesnake-plantains are another group of interest. All four of Ontario's species are known from the Park. Checkered Rattlesnake-plantain (Goodyera tesselata) is likely the most abundant, followed by Dwarf Rattlesnake-plantain (Goodyera repens). Downy Rattlesnake-plantain (Goodyera pubescens) is rare and only known from the West Side. Western Rattlesnake-plantain (Goodyera oblongifolia) is only known from three or so West Side records. 

Checkered Rattlesnake Plantain (G. tesselata)

Lesser Rattlesnake Plantain (G.repens)

Downy Rattlesnake Plantain (G. pubescens)

Western Rattlesnake-plantain (G. oblongifolia) (Bruce Peninsula, ON)

Fen Orchid (Liparis loeselii) is another rarity in Algonquin Park, although there are records throughout. I have not seen this species in the Park. I have to wonder if its habitat requirements are particular, and perhaps the required nutrients just are not common in Algonquin Park. 

Fen Orchid (L. loeselii) (Puslinch, ON)

There are two species of adder's-mouth that are found in Algonquin Park. The first is Green Adder's-mouth (Malaxis unifolia), which, while not common, is found throughout. This is a tiny, delicate orchid that is always a delight to see. The second is White Adder's-mouth (Malaxis brachypoda). This species appears to be a calciphile (likes calcium-rich substrates), so it is not found widely in Algonquin Park. In fact, the only area it is known, to my knowledge, is in the Brent Crater on the East Side. The Brent Crater is unique in that it hosts the only visible limestone (a calcium-rich rock) in the park, so there are a few floristic elements that reflect this. I haven't seen this species in the Park, but have photographed it in the Ottawa Valley, growing in a cedar swamp, similar habitat to which it would occur in Algonquin . 

Green Adder's-mouth (M. unifolia)

White Adder's-mouth (M. brachypoda) (Arnprior, ON)

The twayblades are a favourite group of mine. None of them are common. Heart-leaved Twayblade (Neottia cordata) is the only species found on both the West and East Sides. It grows in shaded bogs. Broad-lip Twayblade (Neottia convallarioides) is found in a few spots on the West Side, and Auricled Twayblade (Neottia auriculata) is found in a few spots on the East Side, both in riparian habitats. Southern Twayblade (Neottia bifolia) is the real crown jewel, and is likely the rarest species of plant in the Park, ranked S1 in Ontario. It is found on the East Side. There's so much more I could say and speculate about the ecology of Southern Twayblade, however I'll omit it here in fear of saying too much :)

Auricled Twayblade (N. auriculata)

Southern Twayblade (N. bifolia)

Southern Twayblade (N. bifolia) — "bifolia"

Now into the bog orchids, buckle up. 

Tall Northern Green Orchid (Platanthera aquilonis) is rare throughout the Park. White-fringed Orchid (Platanthera blephariglottis) is another mega rarity in the Park. It is only known to be extant in one location, and is considered historical from the West Side. Truly a special species. The most common of the bog orchids is Club-spur Orchid (Platanthera clavellata) is is found in most suitable habitats. Tall White Bog Orchid (Platanthera dilata) is quite rare in the Park, only known from one location on the East Side. Northern Tubercled Orchid (Platanthera flava var. herbiola) is rare, but can be found locally abundant along the Petawawa River system on the East Side of the Park. Hooker's Orchid (Platanthera hookeri) has earned the designation of "common" in the checklist, however I doubt this is actually the case. All the records are from the East Side of the Park. Ragged Fringed Orchid (Platanthera lacera) is rare, but can be found in the right habitat, often fens or bogs. Blunt-leaved Orchid (Platanthera obtusata) is quite uncommon and widespread. Lesser Round-leaved Orchid (Platanthera orbiculata) is the species of bog orchid you are most likely to encounter in the forests, where it is uncommon. Finally, Small Purple Fringed Orchid (Platanthera psycodes) is only known from the East Side, where it is not particularly uncommon. 

White-fringed Orchid (P. blephariglottis)

White-fringed Orchid (P. blephariglottis)

Club-spur Orchid (P. blephariglottis)

Tall White Bog Orchid (P. dilatata) (Ottawa Valley, ON)

Northern Tubercled Orchid (P. flava var. herbiola)

Hooker's Orchid (P. hookeri) (Arnprior, ON)

Ragged Fringed Orchid (P. lacera)

Blunt-leaved Orchid (P. obtusata) (Longridge Point, ON)

Lesser Round-leaved Orchid (P. orbiculata)

Small Purple-fringed Orchid (P. psycodes)

Likely the most abundant bog dwelling orchid is the Rose Pogonia (Pogonia ophioglossoides). This species adorns bog mats in shades of pink during the early summer, and is often quite numerous. 

Rose Pogonia (P. ophioglossoides)

Lastly, we have the ladies'-tresses, which made late summer exciting for the botanist. Four species can be found in Algonquin Park. The most abundant is Sphinx's Ladies'-tresses (Spiranthes incurva), part of the Nodding Ladie's-tresses (Spiranthes cernua) complex—it was formally known under this name. This species can be found quite readily in the latter half of August, often growing abundantly in wet areas, including the ditches of Highway 60. The most impressive showing I have seen of this species is along the shore of Lake Travers. Northern Slender Ladies-tresses (Spiranthes lacera) are locally common. This species seems to like dry, open areas. I have seen this species in good numbers the the Old Airfield. Hooded Ladies'-tresses (Spiranthes romanzoffiana) is only known from the West Side, but must certainly occur on the East Side too. This species likes wet areas, so is most likely to be seen in fens. Finally, Cases' Ladies-tresses (Spiranthes casei), which bit of an enigma for me. It is considered quite uncommon in Algonquin Park. I have spent a fair amount of time looking for the species in suitable habitat (dry, open areas), but have so far come up empty. Supposedly, it flowers the latest of these four species. 

Sphinx's Ladies'-tresses (S. incurva)

Hooded Ladies'-tresses (S. romanzoffiana)

Hooded Ladies'-tresses (S. romanzoffiana) — note "fiddle-shaped" lip

Northern Slender Ladies'-tresses (S. lacera)

Northern Slender Ladies'-tresses (S. lacera)

Of course, part of the fun of botany is finding new things. There are a few species that could still be found in Algonquin Park, and I will highlight some here.

Two species that very well may already have been observed in the Park, but have not been confirmed via adequate photos and/or specimen are Green Bog Orchid (Planathera huronensis) and Large-leaved Bog Orchid (Platanthera macrophylla). In just the last couple of years, for example, I know that a likely individual of the former has been seen in Basin Depot, and the latter, a good candidate individual comes from near Galeairy Lake. Green Bog Orchid in particular is a glaring hole in the list, as it is likely one of the more abundant bog orchids in the province.

Green Bog Orchid (P. huronensis) (Cochrane, ON)

Now for some other potential additions—there aren't many! Starting with the most far-fetched...Yellow Lady's-slipper (Cypripedium parviflorum). This species prefers calcium-rich environments, which are lacking in Algonquin Park. Despite the low possibility of its occurrence, I include it simply because of how distinct and conspicuous it is—if its there, it will be seen. Like the White Adder's-mouth, if it is anywhere, it would probably be in the Brent Crater. That being said, I don't think that the Bonnechere River Valley in Basin Depot should be excluded from the list of possibilities. This is a good segue into the next species, Showy Lady's-slipper (Cypripedium reginae). I suspect this is another species with calciphilic tendencies. There is an iNaturalist record from Round Lake, which is tantalizingly close to Algonquin, and in particular, where I suspect it could occur—Basin Depot. In conversation with Dan Brunton, Basin Depot seems to have some sort of calcaerous element to it (the two of us found Bromus kalmii there last August, only the second record for the park, and a species associated with more nutrient rich environments), and it is largely unexplored by botanists, so who knows! As the name would suggest, the species is quite noticeable, so it won't be a matter of overlooking it. Lastly, I have my top pick for most likely addition, Shining Ladies'-tresses (Spiranthes lucida). This species stays true to the common theme here of prefering calcareous habitats, which does slightly hurt the chances of it being in the Park. That being said, it is fairly small, and easy to overlook. I observed this species fairly abundantly along the Ottawa River last June (it is the earliest flowering Spiranthes), and it sort of planted the seed in my mind that it could occur along one of the East Side rivers in Algonquin Park. The two places that immediately come to mind are the Barron and Petawawa Rivers, tributaries of the Ottawa River. These rivers also reside along geologic fault lines, which may mean there is a bit of calcium here and there (while not super common, there are a few calciphilic plants along these rivers). A fun thought, anyways! 

Yellow Lady's-slipper (C. parviflorum) (London, ON)

Showy Lady's-slipper (C. reginae) (Ottawa Valley, ON)

Shining Lady's-tresses (S. lucida) (Arnprior, ON)

And just so I can say "I told you so" when one of these randomly pops up out of the blue in true Algonquin Park fashion, keep an eye out for Fairy-slipper (Calypso bulbosa) and Small Round-leaved Orchis (Galeris rotundifolia). Both have historic records from the Ottawa Valley, so why not...one can dream.

So there you have it, the Orchids of Algonquin Provincial Park. What a wonderful place to observe these wonderful plants that provide endless joy in discovering, as well as crucial information on the habitats in which they occur.