Lichens exhibit both sexual and asexual reproduction. Sexual reproduction involves the production of spores, while asexual reproduction occurs through fragmentation or the formation of specialized structures like soredia or isidia.

Squamulose lichens are not a recognized major group of lichens. The three main groups are crustose, foliose, and fruticose lichens.

Lichens play multiple roles in the ecosystem. They are primary producers, synthesizing organic matter through photosynthesis. They also act as decomposers, breaking down organic matter and releasing nutrients into the soil. Additionally, some lichens have the ability to fix atmospheric nitrogen, making it available to other organisms.

Usnea longissima, also known as 'Old Man's Beard,' is a fruticose lichen characterized by its long, hair-like strands that hang from tree branches.

Lichens play a crucial role in air quality by absorbing pollutants like heavy metals and nitrogen oxides from the atmosphere. They also release oxygen through photosynthesis and contribute to cloud formation by releasing water vapor into the air.

Cladonia rangiferina, also known as 'reindeer lichen,' is a widely distributed lichen species that serves as a primary food source for reindeer and caribou in Arctic and subarctic regions.

Lichens play a crucial role in the nitrogen cycle by fixing atmospheric nitrogen and converting it into a usable form for plants and other organisms. This process is essential for maintaining the balance of nitrogen in ecosystems.

Letharia vulpina, also known as 'Wolf Lichen,' is a foliose lichen characterized by its large, lobed thallus and bright yellow-orange color.

Lichens play a significant role in the carbon cycle by sequestering carbon dioxide from the atmosphere and storing it in their tissues. This process helps regulate the global carbon balance and mitigate climate change.

Roccella tinctoria, also known as 'Dyer's Lichen,' is a fruticose lichen that has been traditionally used as a source of natural dyes, particularly for producing purple and red colors.

Lichens play a crucial role in the rock cycle by weathering rocks through the release of organic acids and other compounds. This process helps break down rocks into smaller particles, making them more susceptible to erosion and further weathering.

Lobaria pulmonaria, also known as 'Lungwort Lichen,' is a foliose lichen characterized by its large, lobed thallus and intricate patterns on its surface.

Lichens play a crucial role in the soil ecosystem by contributing to soil formation, stabilizing soil structure, and facilitating nutrient cycling. They help break down organic matter, release nutrients into the soil, and create microhabitats for other organisms.

Cladonia rangiferina, also known as 'Reindeer Lichen,' is a fruticose lichen that serves as a primary food source for reindeer and caribou in Arctic and subarctic regions.

Lichens play a crucial role in the water cycle by filtering pollutants from water, storing water in their tissues, and releasing water vapor into the atmosphere through photosynthesis. They contribute to the overall balance and regulation of the water cycle.