cushions grip the exposed sunny rocks
- Size
- Height: 1–3 cm
- Lifespan
- 5–15 years
- Diet
- Photosynthetic. Draws energy from sunlight. Requires stable rock surfaces, good light, and well-drained conditions. Tolerates sun, wind, drought, and extreme temperatures.
- Habitat
- Grows on rocks, stone walls, and boulders in exposed, sunny locations. Forms small, dense, grey-green cushions that grip rock tightly.
- Range
- Found throughout North and South Islands on rocks, stone walls, and boulders. Most common in South Island high country and North Island volcanic plateau. Also found worldwide.
- Endemism
- Native
- Main Threats
- None significant. Common and widespread on rocks and stone walls. Localised threats include quarrying, removal of stone walls, and climate change affecting moisture.
- Population
- Not Threatened. Common on rocks, stone walls, and boulders throughout New Zealand. Widespread species found in temperate regions around the world.
- Conservation Status
- Not Threatened
- Human Risk
- harmless
- Handling Note
- rock moss, safe to handle
- Conservation Note
- Native moss; not assessed by NZTCS as bryophytes are generally outside the scope of current threat classifications.
- Te Ao Māori
- No recorded Māori name distinguishes grimmia rock moss from other mosses. Mosses were generally called pūkohu or rimu. Grey-green cushions on rocks would have been noticed. Looked like moss of stone. Like fur of earth. No distinct name survives. Not used as medicine or dye. Too small. Too tenacious. Too tightly bound to rock. Simply part of stone. Quiet, gripping presence.
Try to scrape it off. You will fail. Grimmia pulvinata looks like it is holding on for dear life. Its stems are short and densely packed. Forming small, rounded, grey-green cushions on the rock. The leaves are narrow and pointed. With a long, white, hair-like tip called an awn. Extends beyond the leaf tip. These white tips give the cushions a hoary, frosted appearance. Like they have been dusted with snow. When dry, leaves curl inward. Cushions shrink and turn dark. When wet, leaves unfurl. Cushions expand and turn bright green. It is the moss of the tight grip. Holds onto rock like last stable thing.
What makes it special is the grip. Grimmia rock moss is one of the most tenacious mosses in New Zealand. Grows on bare rock. On vertical stone walls. On tops of boulders. Places with no soil. No organic matter. Nothing but hard stone. It holds on with rhizoids. Root-like structures penetrating microscopic pores of rock. Anchoring it firmly. You can try to scrape it off. And you will fail. It is the moss of the stone. Grips like it will never let go. Learned to thrive where nothing else can.
Leaves are narrow and pointed. With long, white, hair-like tip. Leaf margins are recurved. Curled under. Leaf surface is smooth. White tips reflect sunlight. Protecting moss from drying out. Under hand lens, white tips are beautiful. Each one a tiny glassy thread extending from leaf.
Biologically, it reproduces by spores. Released from capsules on short stalks. Capsules hidden among leaves. Often hard to see. Spores are tiny. Carried by wind to new rocks.
To find grimmia rock moss is to find small, grey-green cushions on rock. They grip tightly. Bristling with white hair-like tips. Try to scrape them off. See how they hold on. It is the moss of the tight grip. Holds onto rock like last stable thing. Proves most successful strategy is sometimes just to hold on and never let go. It carries on regardless.