[4] It has a strong single costa that extends up two thirds of the leaf in both stem and branch leaves.

[4] Sporophytes have red-brown seta and brown sporangia lacking an annulus at mouth of sporangium.

[3] Sporophyte structures are rarely found, this moss more readily reproduces asexually through fragmentation.

[4][6] W. exannulata has a high amount of phenotypic plasticity depending on what kind of habitat it is growing in.

[3][4] The high latitude range of this moss has made it the subject of research looking at increasing UV-B effects due to climate change.

[8] W. exannulata grows in mineral rich fens, swamps, bogs, and peatland environments where soils are slightly acidic.

W. exannulata frequently found in freshwater pools that are driven by rain, snowmelt or glacier-melt in arctic and alpine regions.

[4] It also grows abundantly along edges of pools and lakes among other bryophyte species like Sphagnum moss.