''Pseudoditrichum'' is a rare North American genus of haplolepideous moss (

Dicranidae The Dicranidae are a widespread and diverse subclass of mosses in class Bryopsida, with many species of dry or disturbed areas. They are distinguished by their spores; the peristome Peristome (from the Greek ''peri'', meaning 'around' or 'about' ...

). It is the only known genus in its family (Pseudoditrichaceae), and there is only one species in the genus. ''Pseudoditrichum mirabile'' has been found only in a small area along the Sloan River near

Great Bear Lake Great Bear Lake ( den, Sahtú; french: Grand lac de l'Ours) is a lake in the boreal forest of Canada. It is the largest lake entirely in Canada (Lake Superior and Lake Huron are larger but straddle the Canada–US border), the fourth-largest ...

. This is in the Northwest Territory in northern Canada, only a few kilometers south of the Arctic Circle. ''Pseudoditrichum mirabile'' is unusual in that the combination of the gametophyte features and the sporophyte morphology do not match any other moss family. The entire plant is a mere 3 mm tall, growing on moist silt, generally underneath '' Populus''. It spreads vegetatively by means of spherical underground tubers as well as via narrow, thread-like gemmae. Spores are 15-21 μm long, shed one at a time.Flora of North America, ''Pseudoditrichum mirabile'' Steere & Z. Iwatsuki, 1974.
/ref>William Campbell Steere, Zennoske Iwatsuki 1974. Pseudoditrichum mirabile gen. et sp. nov. (Musci: Pseudoditrichaceae fam. nov.), a unique moss from Great Bear Lake, Northwest Territories. Canadian Journal of Botany, 1974, 52(4): 701-705, 10.1139/b74-090
/ref>

References

Bryopsida Bryophyta of North America Monotypic moss genera {{bryophyte-stub