Foliose lichen has a leafy appearance.
Lichens are a type of symbiotic organism made up of a plant-like pair and a fungus. There are three main types of lichen: crustose, foliose, and fructose, each of which has its own shape, structure, and environmental preferences. Intermediate types include leprosis and lichen scamuloticus, among others. These organisms can also be grouped based on the type of environment they prefer to grow in.
Foliose lichen is leaf-shaped and grows in rounded lobed formations.
Each individual lichen is composed of a mycobiont or fungus, combined with a photobiont or phycobiont in the form of green algae or cyanobacteria. The algae or bacteria carry out photosynthesis, providing nutrients to the fungus and giving the lichen its characteristic greenish or bluish color. Both parts of the lichen obtain water and minerals from dust and rain, but some also obtain nutrients from their substrate through their fungal partner.
Lichens form through a symbiotic relationship between algae and fungi.
Not all types of lichen look the same. Crustoses are flat and unlobed, with a strong grip on their substrate, and can be difficult to remove from the rock or tree they grow on. Leafy lichens have a more leafy appearance, as their name suggests, and are made up of two thin sheets of fungus with algae in the center. They grow in round lobed formations and are easier to remove from their substrate as they are only attached by small rootlets. Fructicose, or bushy lichen, has small round branches made of fungi with algae inside and an unusual upright growth pattern that can resemble a beard or small bush.
Other types of lichens include lichen leprosum, which forms powdery masses, largely unstructured and without a smooth surface. Placodioid lichens are lobed or loose at the edges and close-knit in the center, making them an intermediate form between crustose and leafy lichens. Another intermediate form, the scamulosa lichen, has many minute lobes. Dimorphic lichens have characteristics of both scaly and fruiting lichens, with small lobes bearing tiny stems or branches.
The environmental grouping divides lichens into seven main categories. Several types of lichens grow on plants and are called epiphytes. In this group are the choricolic lichens, which prefer to grow on the trunks of trees, as well as the ramicolic lichens, which inhabit the branches. Musicocolous lichens grow on living moss and follicolous lichens prefer evergreen leaves. Both types are ephiphytic, but the legnicolous, saxicolous, and terrestrial lichens, which inhabit wood, rock, and soil, respectively, are not epiphytic.