sphagnum bog moss holding twenty times its weight in water
- Size
- Height: 10–30 cm
- Lifespan
- 10–20 years
- Diet
- Grows in bogs, fens, and damp peaty ground. Requires consistent moisture, acidic conditions, and protection from direct sunlight. Forms dense, spongy cushions that can hold large amounts of water.
- Habitat
- Grows in wetlands, bogs, and damp depressions where the water is acidic and the ground is soft. Forms dense, spongy mats that can hold up to 20 times their weight in water. The engineer of the wetland, turning open water into solid ground.
- Range
- Found throughout the North and South Islands in bogs, fens, and damp peaty ground. Most common in areas with high rainfall and acidic soils. Also found in temperate regions worldwide.
- Endemism
- Native
- Main Threats
- None significant. This species is common and widespread in bogs and fens. Localised threats include drainage of wetlands and climate change reducing water levels. Classified as Not Threatened.
- Population
- Not Threatened. Sphagnum moss is common in wetlands and bogs throughout New Zealand, particularly in the South Island's high country and the North Island's volcanic plateau. It is a keystone species of bog ecosystems.
- Conservation Status
- Not Threatened
The one that makes the ground squishy has stems that are upright, reaching 5 to 15 centimetres in height, with branches arranged in clusters around the stem. The leaves are small and overlapping, with large, dead, water-holding cells (hyaline cells) that give the moss its remarkable capacity to absorb and retain water. The colour is pale green to yellowish-green, sometimes with a hint of pink or red. It forms dense, spongy mats that can cover hectares of wetland, holding water like a giant sponge. It is the moss of the squishy ground, the one that makes your feet sink.
What makes it special is the water-holding capacity. Sphagnum bog moss can hold up to 20 times its dry weight in water, a living sponge that can absorb and retain moisture like no other plant. The secret is in the leaves, which are made of two types of cells: large, dead, water-holding cells (hyaline cells) and small, living, green cells (chlorophyllose cells). The hyaline cells have pores that draw in water through capillary action, holding it like a tank. The chlorophyllose cells do the photosynthesis. It is the moss of the wetland, the one that builds its own habitat, the one that creates the conditions for its own survival.
The sphagnum bog moss also acidifies the water around it. It releases hydrogen ions in exchange for nutrients, making the environment more acidic. This acidity slows down the decomposition of organic matter, allowing peat to accumulate. Over thousands of years, sphagnum bogs can build up layers of peat many metres thick. It is the moss of the deep time, the one that has been building bogs for millennia.
Biologically, the sphagnum bog moss reproduces by spores, released from capsules on short stalks. It also reproduces by fragmentation, pieces broken off can grow into new plants.
To find sphagnum bog moss is to find the spongy ground. It is soft, wet, and spongy, a living sponge under your feet. You can press your hand into it and feel the water squish up around your fingers. It is the moss of the wetland, the one that holds water like a grudge and builds entire wetlands doing it, the one that proves that the most humble plants can shape the landscape.