lichens

Lichens - Lichens are a group of aberrant organisms formed by a symbiotic association of algae and fungi. The fungi component is called mycobiont and the alga component is called phycobiont . The two components are involved in an inseparable symbiotic association. The fungal com..

This is a group which has two varieties of plants, an alga and a fungus living in perfect harmony. They co-exist for mutual benefit. This relationship is known as symbiosis. The fungus absorbs water and mineral salts and supplies it to the alga. The alga prepares food and supplies it to the fungus..

Lichens are a group of aberrant organisms formed by a symbiotic association of algae and fungi. The fungi component is called mycobiont and the alga component is called phycobiont. The two components are involved in an inseparable symbiotic association. The fungal component provides..

which have a flattened thallus, resembling crusts, attached to the substratum partially or completely. E.g., Graphis, Verrucari..

Lichens are grouped into 3 classes based on the participating fungal component 1. ASCOLICHENS, in which the fungal component belongs to Ascomycetes. 2. BASIDIOLICHENS, in which the fungal component belongs to Basidiomycetes. 3. LICHENS IMPERFECTI, in which the fungal component b..

a) Climax vegetation consists of needle leaved evergreen trees. Dominant species are - spruce, pine, fir, cedar, birch, etc which are able to tolerate wide fluctuations in temperature, light and soil conditions. b) Forest is stratified into an evergreen tree stratum (40 - 70 feet high), a short shr..

Pollution of the atmosphere with industrial gases has been found to result in as much as 15% loss. Soot can block stomata and reduce the transparency of the leaves. Some of the other pollutants are ozone and sulphur dioxide. In fact, lichens are very sensitive to sulphur dioxide in the a..

The plant body is not differentiated into stem, root and leaves but is in the form of an undivided thallus. Vascular tissues are absent. The reproductive organs are single-celled and there is no embryo formation after fertilization. This division includes three sub-divisions: algae, fungi ..

a) Crustose - lichen stage Lichen species like Graphis Rhizocarpon, Rinodina and Lacanora forms the pioneer community in a lithosere, as they can tolerate desiccation. Organic acids produced by lichens corrode the rock surface and release minerals for proper growth o..

Deciduous forests usually have distinct five layers. 1) an overstory of deciduous trees with crown tops about 15 - 55 meters above the ground. 2) deciduous tree stratum with crown tops around 6 - 12 meters above the ground. 3) shrub layer upto 3 meters high. 4) herbaceous layer with rhizomes and bu..