phycobiont
/ˌfʌɪkəʊˈbʌɪɒnt/Botany
noun
1The algal component of a lichen; any alga which is associated with a fungus to form a lichen (occasionally: specifically a green alga, as distinct from a blue-green alga).
2An alga in association with another type of organism (usually a plant).
Origin
1950s. From phyco- + -biont.