A lichen may be composed of members of which two kingdoms?
Lichen is a composite of fungi and algae or cyanobacteria. So there is a mycobiont and a photobiont in lichen, belonging to two/three different kingdoms, BUT all lichens are classified within kindom of fungi .
Close to 20,000 lichens are identified but number of algae/cyanobacterial genera associated with them are no more than 40 to 50.
Fungi are in kingdom Mycota, algae are in kingdom Protista (or in kingdom Plantae), while cyanobacteria belong to kingdom Monera.