Phycobiont in Lichen
The algal component in lichen is known as the phycobiont. Lichens are a symbiotic relationship between a fungus (mycobiont) and an alga or cyanobacterium (phycobiont).

Role of Phycobiont
1. **Photosynthesis**: The phycobiont is responsible for photosynthesis in the lichen symbiosis. It utilizes sunlight to produce energy for the lichen.
2. **Nutrient exchange**: The phycobiont provides sugars and other organic molecules to the fungus, while the fungus provides minerals and protection to the phycobiont.
3. **Environmental adaptation**: The phycobiont helps the lichen adapt to harsh environmental conditions such as extreme temperatures, high altitudes, and polluted environments.

Types of Phycobionts
1. **Algae**: The most common phycobionts in lichens are green algae. They are photosynthetic organisms that provide energy to the lichen through photosynthesis.
2. **Cyanobacteria**: Some lichens have cyanobacteria as their phycobionts. These bacteria are also photosynthetic and help the lichen survive in nitrogen-poor environments.

Importance of Phycobiont
The phycobiont plays a crucial role in the survival and growth of lichens. Without the phycobiont, the lichen would not be able to produce energy through photosynthesis and would die. The symbiotic relationship between the fungus and the phycobiont allows lichens to thrive in a variety of habitats worldwide.