Platanthera obtusata (Banks ex Pursh) Lindl. subsp. obtusata

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 : 34

Platanthera obtusata (Banks ex Pursh) Lindl. subsp. obtusata Fig. 6

Habenaria obtusata (Banks ex Pursh) Richards

Lysiella obtusata (Banks ex Pursh) Rydb.

Common name.

Northern bog orchid

Distribution.

Boreal North America

Comments.

This is the first record for this genus and species, and the second species of orchid discovered (see Corallorhiza trifida ), in the CAA ( Aiken et al. 2007). The species is currently considered to include two subspecies; all North American plants belong to subsp. obtusata , while Eurasian plants are treated as subsp. oligantha (Turcz.) Hultén ( Sheviak 2003, Elven et al. 2011). This wide-ranging boreal species of damp or wet, turfy places ( Correll 1978) is also found beyond the treeline in Canada from northern Yukon to northern Quebec ( Porsild and Cody 1980, Cody 2000, Cody et al. 2003, Sheviak 2003, Saarela et al. 2013a). Porsild (1955) suggested that the species is likely to be found in southern areas of the western Arctic Islands, but it has not yet been found there. In Arctic Quebec, the species has been reported as occurring along the east coast of Hudson Bay ( Polunin 1940, Porsild and Cody 1980, Sheviak 2003, Houle 2013) and at five sites on the north-central Ungava Peninsula ( Maycock and Matthews 1966, Blondeau and Cayouette 2002, Houle 2013). Blondeau and Cayouette (2002) reported the species from two sites near Douglas Harbour along the northern coast, just south of Kimmirut, Baffin Island (mapped in Houle 2013). At one site the species was uncommon at the base of a scree slope along a stream margin, and at the second only a few individuals were found growing among rocks.

Along the Soper River on southern Baffin Island we collected three populations. The first (Saarela et al. 2197) had two subpopulations with a total of 80 plants, the second (Saarela et al. 2209) came from a population of over 100 plants in a 10 m2 area, and the third (Saarela et al. 2488) was from a population of over 250 plants in a 80 m2 area. Near the third population was an even larger population estimated at over 1000 plants that was not collected. These populations were found in moist sedge-willow hummocks set on small hills and valleys on the lower slopes of the Soper Valley away from the banks of the Soper River, growing in association with Betula glandulosa , Salix arctophila Cockerell ex A. Heller, Salix calcicola Fernald & Wiegand, Salix reticulata , Empetrum nigrum L., Rhododendron lapponicum (L.) Wahlenb., Equisetum arvense L., Cassiope tetragona (L.) D. Don, Vaccinium uliginosum L., and Vaccinium vitis-idaea L. While the first two populations were encountered within a few kilometers of each other, we encountered the third, largest population 20 kilometers away, suggesting that other populations may occur in the area where habitat is suitable.

Specimens examined.

Canada. Nunavut: Qikiqtaaluk Region, Baffin Island, Katannilik Territorial Park Reserve, Soper River valley, W bank, ca. 12 km S of Mount Joy, meadow along river opposite Group/Warden Cabin #7, 63°9'50"N, 69°40'2"W, 40 m, 8 July 2012, Saarela, Gillespie, Sokoloff & Bull 2197 (CAN-601651); Qikiqtaaluk Region, Baffin Island, Katannilik Territorial Park Reserve, Soper River valley, W bank, ca. 1 km S of Mount Joy, moderate S-facing slope, 63°9'39"N, 69°40'29"W, 55 m, 8 July 2012, Saarela, Gillespie, Sokoloff & Bull 2209 (CAN-601276); Qikiqtaaluk Region, Baffin Island, Katannilik Territorial Park Reserve, Soper River, 18.5 km downstream (S) of its confluence with the Livingstone River, 2 km S of Emergency Cabin #8, W side of river, 62°59'28"N, 69°43'30"W, 67 m, 15 July 2012, Saarela, Gillespie, Sokoloff & Bull 2488 (ALA, CAN-601652, O).