Algae
Algae and cyanobacteria
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Green algae are simple plants, with chlorophyll and therefore able to produced sugars by photosynthesis. Many are found in freshwater as either single cells or filaments. Sea weeds are the familiar marine large algae with more structure. Algae generally require wet places, but some can survive on land, usually in damp, shady places.
Cyanobacteria were formerly classified as blue green algae but are now regarded as photosynthetic bacteria. Apart from their free living states, many algae and cyanobacteria exist in symbiosis with fungi as lichens, which allow algae to withstand severe drought and to colonise a wider variety of land habitats.
