Lichens

KEY IDENTIFICATION FEATURES Lichens are a particular bright orange colored lichen with an orderly, ring-shaped, thallus. The thallus doesn't have a true root, stem or leaf. This lichen has a widely separated cup shaped fruit body called the apothecia that frequently exists towards the center of the thallus.

DESCRIPTION- Scientists described the lichens as "dual organisms" because of their associations between two or more entirely different types of fungi and lichens.

There are many examples of dissimilar organisms consorting in nature, but lichens are unique because they look and behave quite differently from their component organisms. So, science regards lichens as organisms in their own right and give them generic and species names. For classification purposes the names are really fungal name.

DISTRIBUTION- About 15,000 species of lichens exist, from the tropics to the polar regions. Some species of lichen grow abundantly on tundra soils. These lichens serve as a necessary winter food for animals like the reindeer and caribou in the Arctic and sub-Arctic regions.

THE TYPES OF LICHENS Science groups the lichens into four broad categories. Foliose lichens have a flat, leaf like structure. It grows on the twigs of a shrub. The lobes, about 1/3 of an inch in diameter are silver, grey on top and the bottom appears black because it has dried, but it rapidly becomes blue, green when it becomes wet again.

Fruiticose lichens have a standing, bushy structure. Fruticose and squamulose lichens grow on wooden posts. This lichen has a branched, string like thallus that hangs down that grows in peat soils. This lichen has a scale like form and produces stand up stalked cups while the edges show red fruits of the fungi. Squamulose lichens have a thallus consisting of minute scales.

Crustose lichens grow on or beneath rocks or on trees colored green and white. Some of these lichens will grow on a wall. Also present are many fruits of the fungi colored pale brown.

THE LICHEN PARTNERSHIP A few lichen fungi are members of a fungal group but most produce a fungal fruiting body usually disk shaped in structures. Almost half of the fungi in the world have spores like yeast and mildews and nearly half of these are found only in lichens. The most common lichen fungi are single celled green algae which are found in many lichens of temperate and Arctic, alpine regions. Lichens can be formed by more than one type of fungus and must have developed individually on various occasions.

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