Corallorhiza trifida Chatelain, 1760

Gillespie, Lynn J., Saarela, Jeffery M., Sokoloff, Paul C. & Bull, Roger D., 2015, New vascular plant records for the Canadian Arctic Archipelago, PhytoKeys 52, pp. 23-79 : 31-34

Corallorhiza trifida Chatelain Fig. 5

Common names.

Northern coralroot, early coralroot

Distribution.

Circumboreal-polar

Comments.

Our collections represent the first record of the species in the western CAA, and the second for the eastern CAA and Baffin Island. Thought to be the only orchid in the CAA ( Aiken et al. 2007, but see Platanthera obtusata ), it was previously known from only one collection and two sites in Auyuittuq National Park, Baffin Island ( Gould 1997). Common throughout boreal Canada, its range is scattered and sparse north of the tree-line to the mainland Arctic coast from the Yukon to Bathurst Inlet, Nunavut, and along the Hudson Bay coast ( Porsild and Cody 1980). In their treatment of Corallorhiza trifida for the Flora of North America, Magrath and Freudenstein (2002) reported the species from the western CAA. They mapped two dots on Victoria Island: one centered on the Cambridge Bay area, the other on south-central Victoria Island; and they shaded the southern half of Prince of Wales Island. We are not aware of specimens or other literature reports for these records; they do not appear in Freudenstein’s (1997) revision of Corallorhiza in North America, nor does J. Freudenstein (pers. comm. 2014) know the source of these records (L. Magrath, first author of the FNA treatment, is deceased). Our collection from south-central Victoria Island (incidentally, this is one of the same areas mapped in Magrath and Freudenstein 2002) is the only confirmed record for the western CAA. It was recorded as uncommon on the low, densely vegetated, south-facing bank of a creek near its mouth, on a mostly sandy substrate, with Dryas integrifolia , Bistorta vivipara (L.) Gray, and Hedysarum boreale subsp. mackenziei (Richardson) S.L. Welsh ( Salix and Arctous rubra (Rehder & E.H. Wilson) Nakai nearby).

In the Soper River valley on southern Baffin Island we found the species to be scattered, but never common, on densely vegetated river flats, riverbanks, and peaty wet meadows at several localities. Our three collections increase the number of records for Baffin Island to four. In adjacent northern Quebec, the species occurs along the coast and in the interior, known from only three Arctic localities ( Houle 2013).

The species is a near-complete mycoheterotroph ( Zimmer et al. 2008, Cameron et al. 2009), and in most of its range plants are green to yellow-green in colour (e.g., see photo in Houle 2013: 322). Freudenstein (1997) noted that lighter-coloured individuals tend to occur in more southern, forested areas, whereas darker-coloured forms occur in exposed northern sites, such as tundra. Earlier observations of the species at its northern limits in Canada are consistent with this ( Gould 1997, Saarela et al. 2013a: Fig. 19). Our collection from Victoria Island was prominently reddish-brown throughout (anthocyanic) (Fig. 5A-C); those from the Soper River valley less so (Fig. 5D). None of the populations we observed was as large as a population of 56 individuals found in Auyuittuq National Park of Canada, Baffin Island ( Gould 1997). One population collected and surveyed in the Soper River valley had 19 stems in a 5 × 3 m area (Saarela et al. 1970); the population collected on Victoria Island had 14 stems in two clumps (Gillespie et al. 8093). A fourth occurrence was observed but not collected in the Soper River valley (near confluence of Willow River, ca. 14 km S of Mount Joy, 63°9'24"N, 69°41'35"W).

Specimens examined.

Canada. Nunavut: Kitikmeot Region, Victoria Island, W end of Johansen Bay at mouth of Mackenzie Creek, 68°36'4"N, 111°21'7"W, 0-20 m, 20 July 2008, Gillespie, Saarela, Consaul & Bull 8093 (CAN-592381; Qikiqtaaluk Region, Baffin Island, Katannilik Territorial Park Reserve, densely vegetated river flat near Mount Joy, ca. 5 m wide band between river and dry stony floodplain, 63°14'52.7"N, 69°36'45.7"W, 75 m, 1 July 2012, Saarela, Gillespie, Sokoloff & Bull 1970 (CAN-601648); Qikiqtaaluk Region, Baffin Island, Katannilik Territorial Park Reserve, peaty wet meadow along Soper River, ca. 0.5 km N of Mount Joy, 63°15'3"N, 69°36'6"W, 86 m, 2 July 2012, Saarela, Gillespie, Sokoloff & Bull 2036 (CAN-601649); Qikiqtaaluk Region, Baffin Island, Katannilik Territorial Park Reserve, Soper River, high water mark along riverbank, ca. 13 km downstream (S) of its confluence with the Livingstone River, 62°59'40"N, 69°42'46"W, 35 m, 13 July 2012, Saarela, Gillespie, Sokoloff & Bull 2415 (CAN-601650).