DENDROLOGY

Detailed explanation-1: -Lichens are considered as pioneer species in primary succession on rocks because they can easily grow on rocks where other plants cannot grow. They produce oxalic acid which induced the weathering of rocks and thus soil is formed.

Detailed explanation-2: -In lichens, the interaction between algae and fungi is a symbiotic relationship. Algae feed fungi that lack chlorophyll pigments. Fungi, on the other hand, help algae by providing protection and aiding in water absorption. No one is injured in this form of connection, and both parties benefit from it.

Detailed explanation-3: -Mutualistic interactions between free-living algae and fungi are widespread in nature and are hypothesized to have facilitated the evolution of land plants and lichens. In all known algal-fungal mutualisms, including lichens, algal cells remain external to fungal cells.