### condition | illness | disease:

Lichen
* Every lichen combination of a fungus and algae or algaelike bacteria.
* Many lichens appear gray when dry, but a transformation occurs when wet.
* Many lichens are examples of obligate symbiosis
  - very sensitive to pollution in the air
  - can inhabit harsh environments and withstand prolonged periods of drought
  - produce small powdery granules called soredia on their surface
  - show a remarkable sensitivity to air purity
* Most lichens are dispersed by vegetative propagation
  - extremely vulnerable to air pollution
  - grow slowly and many grow only in a narrow range of habitat conditions
* Most lichens have appearances
  - biodiversity
  - distribution
* Some lichen also have the ability to return valuable nitrogen to the soil
  - are eaten by humans
* Some lichens are able to loosen bits of the rocks where they live by growing into the rock
  - extremely old
  - symbiotic relationships between fungi and green algae
  - unique to old-growth forests
* Some lichens can be hundreds of years old
  - survive severe cold or desiccation
  - contain green algae
* Some lichens have little medical values
  - just break up into fragments when they dry
  - look like paint stains
  - make nitrogen in the air usable to plants
  - provide food for reindeer in the Arctic
  - survive where fog or dew is their only source of water
* are a algae and fungal combination that grow on surfaces that have some moisture
  - good indicator of pollution
  - mutual provident society of fungi and algae
  - mutualistic association between a fungus and an alga or cyanobacteria
  - remarkable partnership between algae and fungi
  - successful alliance between a fungus and an alga
* are a symbiotic association between a fungus and an alga
  - algae and fungus
  - composite of algal cells intertwined with fungal hyphae
  - conjunction of an algae and a fungus
  - relationship between a fungus and a green alga or cyanobacterium
  - union between fungus and algae
  - able to withstand great desiccation without injury
  - abundant with many rare species
  - actually two organisms existing in a symbiotic relationship know as mutalism
* are also important as environmental indicators, especially of air quality
  - in making soil
  - of great use to ecologists
  - present in mature habitats on rock surfaces or the trunks of trees
  - always a symbiotic relationship between a fungus and a photosynthesizer
  - amazing creatures for other reasons as well
  - amongst the most indispensible of all bio- indicators
  - beautiful dual organisms
  - certainly one of the most successful biological marriages on earth
  - common in the Sacramento region
  - complex structures made up of a fungus and an alga living together symbiotically
  - composite, symbiotic organisms made up from members of as many as three kingdoms
  - different
  - division
  - eaten by many animals, such as deer, mountain goats and caribou
  - especially conspicuous as one walks to the falls overlook
  - essentially fungi containing symbiotic algal cells
  - extremely hardy and can survive severe water stress
  - far more than mere biological curiosities
  - friendly relationships between alga and fungi whereby they grow in a plant-like form
  - fungi that work with algae
  - funguses
  - good at colonizing bare rock and starting to break it down into soil
  - greener in damp than in dry weather
  - helpful in monitoring forest conditions like moisture content and effect of pollution
  - highly successful organisms
  - homes for spiders, mites, lice and other insects
* are important for several reasons
  - in the process of soil formation
  - pioneers, breaking down rock and allowing for colonization by other plants
  - in fact a symbiotic lifeform between a fungus and a alga
  - located in forests
  - long-lived and grow slowly
  - low in protein, but high in carbohydrates
  - many times studied in a class when studying the mosses
  - moss-like plants that grow on rocks and wood
* are mutualistic associations between fungi and algae
  - cyanobacteria, green algae, or both
  - often the first life form to colonize bare rock and, as they decay, build soil
  - organisms that consist of a fungus and alga
  - pioneer species
  - placed in groups based on their body forms and features
  - plants made up of an algae and fungi growing together
  - products of a symbiosis between a fungus and a unicellular alga
  - quite flammable and are some of the slowest plants to recover after a fire
  - really sensitive to pollution, and scientists use lichens to test air quality
  - rootless organism, part algae and part fungi
* are sensitive slow growing organisms
  - to air pollution due to their mode of mineral uptake
  - skin diseases
  - slow growing associations between fungi and photosynthetic symbionts
  - soil builders, producing weak acids that very gradually erode the rock surface
  - sparse in high-pollution areas
* are symbiotic associations between Ascomycetes and certain green algae
  - of algae and fungi
  - combinations of algae and fungi that adhere to bark and even rocks
  - forms of plant life than contain an alga and a fungus
  - organisms made up of algae and fungi
  - relationships between algae and fungi
  - symbiotic, non-vascular organisms, similar to fungi or moss
* are the first conspicuous organisms to colonise bare rock surfaces
  - major food for tundra herbivores such as caribou and reindeer
* are the most dominant plants
  - overlooked of the conspicuous organisms in the natural landscape
  - principal winter food of many caribou, reindeer and musk-oxen
  - tough, self-sufficient organisms
  - unique creatures in the plant world
  - useful bioindicators of environmental quality
* are very good bio-indicators to survey the air pollution
  - bioindicators of air quality as they are very sensitive to pollution
  - sensors of environmental pollution
  - resistant to cold and drought
  - sensitive to atmospheric pollution and so are abundant in low-pollution areas
* are very sensitive to pollutants and serve as indicators of air and water pollution
  - in the air and are used as bioindicators
  - sulphur dioxide pollution in the air
  - very, very slow growing
  - well known as dye sources
* belong to the group of spore-plants
  - usually to the most unpretentious organisms
* come in a variety of forms
  - many colors, sizes, and forms
  - three different forms
* comprise algae and fungi in partnership.
* cover the rocks.
* create new soil from rock.
* develop on their surfaces and often cover large spaces on mountain tops.
* grow differently at different times in their lives
  - extremely slowly
  - green on stumps, roots and rocks
* grow in a variety of habitats
  - wide range of habitats on nearly every continent
  - mats on the ground and on rocks across the Arctic
  - unlikely spots such as bare rocks, deserts, dead wood or bark on a tree
* grow on almost any type of surface and can be found in almost all areas of the world
  - bare rockfaces, and tenacious alpine flowers find a precarious roothold
  - rocks and soil, as well as the bark of various trees and shrubs
  - rocks, walls, trees, fences, roofs and on the ground, as well as on leaves
  - soil, trees and memorials
  - very, very slowly
* have a high tolerance for cold, drought and heat
  - truly remarkable resistance to drought
  - variety of different growth forms
  - four growth forms
* have many forms
  - no roots, obtaining moisture instead from the evening air and the dew
  - specific requirements for their habitats
* have the ability to capture fog and dew, thus conserving moisture where water is scarce
  - potential to withstand a wide range of environments
  - very slow growth rates
* indicate the level or air pollution, particularly sulfur dioxide.
* is skin disorder
* look like plants but are actually combinations of two organisms.
* love cold weather.
* make the lettering difficult to read.
* occur in a variety of forms.
* often appear leafy or crusty and are colored gray, green, yellow, or white.
* produce acids that decompose rocks, contributing to the production of soil
  - aromatic acids
* proliferate only on branches and twigs of plants already in decline for some other reason.
* provide many benefits both in nature and in human culture.
* reproduce by releasing packets of fungal and algal cells.
* require no food source other than light, air, and minerals.
* secrete an acid that dissolves some minerals.
* survive an extremely wide range of temperatures.
* tend to absorb chemicals in the atmosphere
  - grow on the inner trunk and branches of deciduous trees and shrubs
* usually reproduce by the breaking off of a segment that contains both components.
* vary greatly in form and structure
  - in their degree of structural organisation
+ Chlorophyta
  * The division contains both unicellular and multicellular species. While most species live in freshwater habitats and a large number in marine habitats, other species are adapted to a wide range of environments. Watermelon snow, or 'Chlamydomonas nivalis', lives on summer alpine snowfields. Others live attached to rocks or woody parts of trees. Some lichens are symbiotic relationships between fungi and green algae.
+ Lichen, Their life habit, Reproduction: Fungi :: Botany :: Bacteria :: Algae :: Extremophiles
  * They make small groups of algal cells surrounded by fungal filaments. These 'soridia' can be blown by wind. Some lichens just break up into fragments when they dry. Wind carries the pieces, which grow when moisture returns. Also, lichen fungi can reproduce sexually by forming fruiting bodies containing spores
  * Lichen are the main winter food for reindeer. In summer they have much more choice of food. Some lichen are eaten by humans. A kind of lichen, which is called 'Iwatake' in Japanese and 'Seogi' in Korean language, is collected from cliffs, and used in various Korean and Japanese foods. Lichen have a high level of acid. Care must be taken, as there are at least two kinds of lichen that are toxic
+ Tundra: Geography :: Biomes
  * Most water on the tundra is frozen within the soil. The permanent frozen soil is called permafrost. Permafrost and fierce winds prevent large trees from growing deep roots. Plants in the tundra are small and grow close to the ground. Plants called cushions grow in tight clumps in the tundra, but lichens are the dominant plants. Lichens cover the rocks. The few trees that do grow on the tundra are dwarf willows and birch.