Grades 3–5 · Organisms
How can a fungus and an alga grow together as a lichen?
A patch of lichen on rock may look like one tiny plant. It is a close living partnership. A fungus forms much of its body, while an alga or another photosynthetic partner lives within that structure.
In the diagramLichen partners share a living structurelightfungal threads around algal cellssugars to funguswater + shelterA common partnership; other microbes can also be present.
The photosynthetic partner captures light energy and uses it to make sugars. Some of this material becomes available to the fungus. The fungus cannot make its own food from sunlight in the same way.
Fungal threads provide a surrounding structure that helps hold water and protect the photosynthetic cells from drying. Together, the partners can live on exposed surfaces where many ordinary plants would struggle to establish roots.
Neither a rock stain nor a kind of moss explains this arrangement. It is a body built through interacting organisms. Different lichen partnerships have different needs, which helps explain their many colors, shapes and growing places.
About this explanation
Starting knowledge: Know that fungi absorb nutrients and that photosynthesis uses light to make sugars.
Sources
- National Park Service — Lichens — Point Reyes National Seashore