Aulacomnium turgidum, commonly called swollen thread-moss or mountain groove-moss, is a species of moss in the family Aulacomniaceae.

It is found in the United States, Canada, Russia, Greenland, Norway and Scotland.

[2][3] The shoots are up to 10 centimeters (4 inches) tall, with scales blunt, concave, 2.5 to 3 millimeters long and densely overlapping, which gives the shoots a swollen, turgid appearance.

It is visually similar to the circumboreal ribbed bog moss (Aulacomnium palustre).

[4] Aulacomnium turgidum grows on alkaline substrates in open habitats on ledges and crags, often in alpine environments.