Lichens have a large variability of growth forms. Traditionally, they are divided into three main morphological groups: fruticose, foliose, and crustose. This classification is artificial, so we can find thalli with convergent forms.
Crustose lichens are thin and tightly attached to their substrate. If you try to sample these lichens without their substrate, you may destroy them. In the first photo, we have Allographa argentata (📷 spielmann.adriano), a crustose lichen that belongs to the largest crustose lichen family, Graphidaceae.
Fruticose lichens are strap-shaped, shrubby, hair-like, and have considerable variation in their branching pattern. They are little attached to their substrates and easy to be collected. Some fruticose lichens can reach more than one meter, such as some Usnea species (📷edsonvandeira).
Foliose lichens are leaf-like and partially attached to their substrate. Their growth is predominantly horizontally, and they can have a great range of sizes. One exemple of foliose lichens is Erioderma cf. leylandii (📷 carlosvidigal_). Erioderma is a genus of gorgeous foliose lichens which are mainly found in the neotropics. They are easily found in humid, cloud, and montane forests also in bush vegetation and can be easily recognized by their hairy thallus and the association with cyanobacteria.
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