ABSTRACT
Lichens represent a stable, well-balanced self-supporting microecosystem. In aquatic habitats, 13,500 algal photobionts are symbiotically associated with 13,780 fungal lycobionts. But 338,000 terrestrial plants engage ~ 360 mycorrhiza species. To obtain water and minerals, the narrow (2 – 20 µm diameter) mycorrhizal hypha, a characteristic of arbuscular type (AM), allows access to a vastly greater area of soil than that of host plants. Hence, the AM promotes faster growth and production of more and heavier seeds in many crops. In ascomycetous lichens, clonal multiplication occurs simultaneously in symbiotic partners together but it occurs as independent units in sexual reproduction. Despite clonality in mycorrhizal hyphae, each daughter fragments inherit different numbers and types of nucleitalic>, as they are scattered throughout the streaming cytoplasm. It is difficult to generalize that all the simpler crustose lichens reproduce sexually alone. In areas receiving heavy precipitation, the clonal multiplication phase is prolonged at the cost of delayed sexual phase. Higher water content of the clonal soredial spores reduces dispersal distance.
