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Bryum argenteum

silvery bryum

Bryaceae Cosmopolitan, worldwide

Drought Tolerant

Native to North America

SunFull Sun – Part Shade

WaterLow · drought-tolerant

Overview

Bryum argenteum is a small, cushion-forming moss recognised by its silvery-green to whitish shoots. The tightly packed leaves overlap and clasp the stem so closely that each shoot looks like a smooth, rounded, worm-like thread 0.1-0.4 inches (2-10 mm) tall. The upper half of each leaf is colourless and translucent, which gives the whole cushion its silvery sheen, especially when dry. It forms low, dense patches from a fraction of an inch to several inches across. Spore capsules are egg-shaped, nodding, and red-brown, carried on short red stalks, appearing mainly in winter and spring. This moss grows almost worldwide on disturbed, often nutrient-rich ground: pavement cracks, walls, rooftops, gravel, compacted soil, and city streets. It withstands drought, trampling, salt, and air pollution that exclude most other mosses, drying to a grey crust and reviving within minutes of rewetting. As a non-vascular plant it has no roots and takes up water over its whole surface, anchoring by thread-like rhizoids. It is among the first plants to colonise bare urban surfaces.

Native Range

Found on every continent, including Antarctica, and across nearly all climates. Its global range has been broadened by human disturbance and the spread of paved, urban habitats.

Suggested Uses

Used on green roofs, in moss gardens, and on gravel, paving, and rockwork where tough ground cover is wanted. It suits dry, sunny, or polluted urban sites that defeat most mosses. It is not suited to deep shade kept permanently wet.

How to Identify

Identify it by compact silvery-green cushions whose shoots are smooth and rounded, with leaves overlapping so tightly that no leaf tips stand out. The silvery or whitish colour, strongest when dry, comes from the colourless upper half of each tiny leaf. Shoots stand only 0.1-0.4 inches (2-10 mm) tall, and it typically grows in pavement cracks and other hard urban surfaces.

Appearance

Colors

Foliage Colors

green

silver

Fall Foliage Colors

no change

Bloom Information

As a moss it does not flower. Red-brown spore capsules nod from short red stalks, ripening mainly in late winter and spring. It also spreads readily from small shoot fragments and specialised bulb-like buds.

Detailed Descriptions

Foliage Description

silvery green to whitish

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 8.0(Neutral)

357912

Soil Types

sand rocky loam chalk

Drainagewell drained

Water & Climate

Water Needs

Low

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Bryum argenteum tolerates a very wide range of conditions, from full sun to shade and from acid to lime-rich surfaces, pH about 6.0-8.0. It grows on thin, gritty, or compacted substrates and on bare rock, masonry, and pavement, needing little more than an occasional wetting. It survives long dry spells by drying out completely and reviving when moisture returns. In cultivation it establishes from scattered fragments pressed onto a firm, gritty surface and kept damp until growth begins. It needs no feeding and grows in places too harsh for most plants. Constant standing water and deep, permanently wet shade suit it less well than open, free-draining sites.

Pruning

No pruning is required. Loose grit or debris can be brushed off so the cushions are not buried. Patches can be lifted and crumbled over new surfaces to spread them.

✓ Toxicity

Non-toxic