A genus of 6-10 species, mycoheterotrophic herbs, of circumboreal distribution. Recent molecular evidence supports its separation as a genus distinct from Monotropa (as has often been done in the past) (Neyland & Hennigan 2004; Broe 2014). These studies also demonstrate that several cryptic to semi-cryptic species should be recognized; plants in North America are not conspecific with those in Eurasia, and at least six species appear to be present in e. North America (Broe 2014; Klooster & Culley 2010; Haines 2011).
Ref: Bidartondo & Bruns (2001); Broe (2014); Haines (2011); Klooster & Culley (2010); Neyland & Hennigan (2004); Stevens et al. In Kubitzki et al. (2004); Wallace (1975); Wallace (2009a) In Flora of North America Editorial Committee (2009). Show full citations.