Which Plants are Two Plants in One?

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A lichen is not a single plant. It is made up of two plants, a fungus and an alga tightly bound together. This coming together of both plants benefits each one. A lichen has an outer layer of dense fungal threads and an inner layer of cells of alga. The fungus protects the alga from wind, frost and sunlight, while the alga, in return, gives the fungus food which it manufactures by photosynthesis. Lichens can be found on rocks or trees. They reproduce by producing a powdery substance that contains pieces of both alga and fungus.

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