Hedwigia spp.
Hoarmosses
Native to North America
Overview
Hedwigia spp. is a genus of mosses in the family Hedwigiaceae, growing on bare, sunny, acidic rock such as granite boulders, outcrops, and stone walls across much of the world. The plants form loose, spreading, wiry mats and tufts, dull grey-green to olive when moist and conspicuously hoary or whitish when dry, because the leaves end in clear, colourless, toothed hair-points. This pale, frosted look when dry gives the common name hoarmosses. The egg-shaped leaves are concave and spread or curl when dry; the genus lacks a midrib, unlike many mosses. Hedwigia spp. grows directly on exposed stone with little or no soil, tolerating extreme heat, drought, and full sun by drying to a pale, brittle state and reviving within minutes of wetting. Spore capsules are rounded and sit nestled among special leaves close to the shoot rather than on long stalks. The genus is a pioneer on bare acidic rock, often growing with lichens, and is absent from limy rock. Spread is by spores and by fragments of the brittle shoots. The hoary dry appearance, lack of a midrib, and acidic-rock habit identify the genus.
Native Range
Hedwigia spp. is widespread across much of the world, growing on bare, sunny, acidic rock such as granite and other siliceous boulders, outcrops, and stone walls, from lowlands to mountains. It favours exposed, dry, acidic stone and is absent from lime-rich surfaces.Suggested Uses
Hedwigia spp. colonises bare acidic rock, boulders, and walls on its own and is studied as a drought- and heat-tolerant pioneer of exposed stone. The genus indicates acidic, siliceous rock and is used in bryophyte study. Its tolerance suits it to naturalistic plantings on acidic stone and to rock and wall features in sun.How to Identify
Appearance
Growing Conditions
Sun Requirements
• 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