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Ulota spp.

curl mosses

Orthotrichaceae

Temperate and cool regions, both hemispheres (epiphytic)

Native to North America

SunFull Sun – Part Shade

WaterMedium

Overview

Ulota spp. is a genus of small cushion-forming mosses in the family Orthotrichaceae, growing mostly on the bark of trees and shrubs, and sometimes on rock, in humid temperate regions. The plants form neat, rounded green to yellow-green tufts about 0.2-0.8 inch (5-20 mm) tall on twigs and trunks. The narrow leaves are spreading when moist but curl and twist strongly inward when dry, giving the cushions a curled, frizzy look that gives some species the name curl-moss. Spore capsules are held upright on short stalks and are ribbed or furrowed when dry, topped by a hairy cap called a calyptra; the capsule mouth has a fringe of teeth that respond to humidity. Ulota spp. is an epiphyte that takes water and nutrients from rain and air rather than the host, doing no harm to the tree. The genus favours clean, humid air and is sensitive to pollution, so it is used as an indicator of air quality. Many species have returned to towns and roadside trees as air quality has improved. Plants survive drying by curling up and reviving when rewetted.

Native Range

Ulota spp. grows across temperate and cool regions of both hemispheres, mainly on the bark of trees and shrubs and sometimes on rock, in humid woodland, hedgerows, and on roadside and parkland trees. It favours clean, humid air.

Suggested Uses

Ulota spp. is used as an indicator of clean air, and its return to town and roadside trees tracks improving air quality. The genus is of interest to bryologists and in air-quality surveys. Cushions on fallen twigs are sometimes used in terrarium and moss displays.

How to Identify

Identify by the small, neat, rounded green to yellow-green cushions on twigs and bark, with narrow leaves that curl and twist tightly when dry and spread when moist. The ribbed capsules on short stalks, capped by a hairy calyptra, are characteristic. The curling dry leaves separate Ulota spp. from the related Orthotrichum spp., which keeps straighter leaves.

Appearance

Colors

Foliage Colors

green

yellow green

Bloom Information

Mosses do not flower. Ulota spp. reproduces by spores from ribbed capsules held upright on short stalks and capped by a hairy calyptra, ripening mainly in late spring and summer. It also spreads by fragments, and cushions enlarge by their own growth.

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Water & Climate

Water Needs

Medium

Care & Maintenance

Care Guide

Ulota spp. grows as an epiphyte on bark and twigs, and sometimes on rock, in humid, well-lit to lightly shaded sites with clean air, taking water and nutrients from rain rather than the host. It survives drying by curling up and reviving when rewetted but declines in polluted or very dry air. The genus is rarely cultivated and is usually seen on trees in clean-air areas. Air pollution and deep shade reduce it. Cushions spread slowly on their own across bark.