Tree lichens are a type of symbiotic organism that consists of a fungus and an alga or cyanobacterium living together. The fungus provides structure and protection, while the alga or cyanobacterium photosynthesizes and provides nutrients. Tree lichens can be found growing on the bark or branches of trees and are important for ecosystem health as they contribute to nutrient cycling and provide habitat for various organisms. **

No, cacti do not have lichens. Lichens are a symbiotic organism composed of a fungus and algae or cyanobacteria, while cacti are a type of succulent plant. Lichens are often found growing on rocks, trees, or other surfaces, but not on cacti. **

Lichens are not harmful to trees. In fact, they are a symbiotic relationship between fungi and algae or cyanobacteria that can actually benefit trees by providing nutrients and aiding in the breakdown of organic matter. While lichens can sometimes be found on stressed or dying trees, they are not the cause of the tree's decline but rather take advantage of the tree's weakened state. Overall, lichens are not harmful to trees and are a natural part of the ecosystem. **

Mycorrhiza is a symbiotic association between a fungus and the roots of a plant. The fungus helps the plant absorb nutrients from the soil, especially phosphorus, in exchange for receiving sugars produced by the plant through photosynthesis. Lichens, on the other hand, are a symbiotic relationship between a fungus and either algae or cyanobacteria. The fungus provides structure and protection, while the algae or cyanobacteria provide food through photosynthesis. Both mycorrhiza and lichens play important roles in nutrient cycling and ecosystem health. **

Lichens in symbiosis have several benefits. They can survive in harsh environments where neither fungi nor algae could survive alone. Lichens can also act as bioindicators of air quality, as they are sensitive to pollution and changes in their environment. Additionally, lichens play a role in soil formation and nutrient cycling, contributing to ecosystem health and stability. **

Lichens exhibit a mutualistic relationship, where both the fungus and the algal or cyanobacterial partner benefit from the association. The fungus provides a protective structure and absorbs water and nutrients, while the algal or cyanobacterial partner photosynthesizes and provides sugars to the fungus. This mutualistic behavior allows lichens to thrive in a variety of environments, from harsh deserts to cold tundras. Additionally, lichens can also engage in a symbiotic relationship with other organisms, such as providing food and shelter for insects. **

The presence of moss and lichens on fruit trees can indicate a few different things. While a small amount of moss and lichens on fruit trees is generally harmless and can even add a natural aesthetic, an excessive amount can be a sign of poor tree health. Moss and lichens can thrive on fruit trees that are stressed, diseased, or lacking proper sunlight and air circulation. Therefore, it's important to monitor the amount of moss and lichens on fruit trees and address any underlying issues that may be contributing to their growth. **

Many people have a negative view of lichens on the pavement because they are often seen as unsightly and can make the pavement appear dirty or unkempt. Additionally, lichens can make the pavement slippery when wet, posing a potential safety hazard. Some people also believe that lichens can cause damage to the pavement over time, although this is not necessarily true. Overall, the presence of lichens on the pavement is often perceived as a nuisance rather than a natural and harmless occurrence. **