Algae: On tree trunks and leaves of evergreen trees and shrubs, algae can be seen as a green, powdery deposit. It is not unattractive on trunks but can make leaves dull and unsightly. The alga Trentepohlia is seen as a vivid orange powdery deposit on tree trunks and branches.
Lichens: Lichens growing on trees and shrubs are mainly grey to green in colour. They may form as crusty patches, leafy mats, or upright branching or hanging growths on the bark or wood.
Moss: Various mosses can grow on the trunks or branches of trees and shrubs. These mosses may form large, coarse, loose, green or yellowish-green tufts, densely matted tufts, or compact green cushions.