Wall screw-moss

Conservation Status

IUCN Red List

LC - Least Concern

NatureServe

NNR - Unranked

Minnesota

not listed

Description

Wall screw-moss is a common, small, tuft-forming moss. It is a cosmopolitan species, occurring on every continent except Antarctica. It occurs throughout the United States and southern Canada. It is found in a variety of habitats, including grasslands and forests, and in a variety of light conditions. It grows on calcareous rocks, including limestone and sandstone, and on compacted soil. It is also found on man-made habitats, including concrete, brick and stone walls, roof tiles, and bridges. It is a synanthropic species, very common in urban and industrial areas, but rarely found in natural settings away from human activity.

Wall screw-moss has an upright growth form (acrocarpous). It forms dense green cushions often topped with a crowded forest of tall, fruiting stalks (sporophytes).

The stems are of the sexual generation (gametophyte) are unbranched and small, no more than ⅜″ (1 cm) tall. Male and female parts occur on the same plant (autoicous).

The leaves are long, narrow, and egg-shaped or elliptic to inversely egg-shaped. The leaf tips may be bluntly pointed or rounded. The central axis (costa) forms a well developed, short to long, hair-like filament (awn) at the leaf tip. The leaves are green but the tuft may appear grayish green due to the long awns. When it is moist, the leaves are widely spreading. As the plant dries, they fold inward and upward, transforming the star-like stem tip into a sharp, pyramidal point formed by the gathered leaves.

The asexual generation (sporophytes) is a prominent feature of this moss in the spring. Each sporophyte consists of a slender stalk (seta) with an equally slender, spore-bearing capsule at the tip. The seta is straight and commonly ¼″ to ⅝″ (6 to 15 mm) long, though in favorable conditions it can be much longer. It is yellowish at first, becoming reddish as it matures. The capsule is cylindric and erect or nearly erect. The spore-bearing portion (urn) is 1⁄16″ to ⅛″ (1.5 to 3 mm) long and straight or very slightly curved (arcuate). The capsule lid (operculum) has a distinct, long beak, which can be straight, curved, or angled up to 90°.

Growth Form

Acrocarpous

Height

Similar Species

Habitat

A wide variety of natural and man-made habitats

Ecology

Phenology

Capsules mature in spring and summer.

Use

Distribution

Sources

3, 24, 30, 83.

Biodiversity occurrence data published by: Minnesota Biodiversity Atlas (accessed through the Minnesota Biodiversity Atlas Portal, bellatlas.umn.edu. Accessed 4/10/2026).

Midwest Herbaria Portal. 2026. https://midwestherbaria.org/portal/index.php. Accessed 4/10/2026.

Biodiversity occurrence data published by: Bryophyte Portal (accessed through the Bryophyte Portal Portal, https://bryophyteportal.org/portal). Accessed 4/10/2026.

Tortula muralis Hedw. in GBIF Secretariat (2023). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org. Accessed 4/10/2026.

Janssens, Joannes A., and The Minnesota County Biological Survey, Minnesota Department of Natural Resources, State of Minnesota. County Atlas of Minnesota Mosses. May, 2000. www.dnr.state.mn.us/plants/flm/mossatlas/index.html.