. Botany for high schools. Botany. SPECIAL ASPECTS OF NUTRITION OF PLANTS 12$. available form for the forest trees. It is supposed that the fungus mycelium obtains some benefit from this association with the roots of trees, but this is not well understood. These mycorhizae are shorter, stouter and also branched more than the normal roots. This difference in form, as well as their more complex structure, renders the name mycorhiza appropriate and useful. In some cases these fungus threads are the spawn of certain mushrooms and puff balls. The mycelium of the truffle, an edible fungus of great c
. Botany for high schools. Botany. SPECIAL ASPECTS OF NUTRITION OF PLANTS 12$. available form for the forest trees. It is supposed that the fungus mycelium obtains some benefit from this association with the roots of trees, but this is not well understood. These mycorhizae are shorter, stouter and also branched more than the normal roots. This difference in form, as well as their more complex structure, renders the name mycorhiza appropriate and useful. In some cases these fungus threads are the spawn of certain mushrooms and puff balls. The mycelium of the truffle, an edible fungus of great commercial value in southern France and in Italy, is supposed to have a similar relation to the roots of certain forest trees. 206. Symbiosis.âThis living together in close physiological relation of two different organisms is called symbiosis. In the case of the root tubercles ^^s- 94. - , . , 1 1 . r 1 Beech root in wood 01 legummous plants the relation is one of mutual humus freed from â i r 1 ⢠1 1 ⢠⢠/ 1 fungus, root hairs h. benefit, each partner in the symbiosis (each partner (After Frank.) is a symbiont) deriving some benefit from the other. The same rela- tion is supposed to exist in the case of the mycorhiza of forest trees. This kind of symbiosis is called miitualistic symbiosis. Another well-known example is seen in the case of the lichens (see paragraph 432). Another kind of symbiosis occurs in the relation of a parasite to its host where the parasite living on or in the host injures or kills it but the host receives no benefit. This is antagonistic symbiosis. So there is contact symbiosis where two organisms living side by side, work together, each one supplying the other with some product of its w^ork. An example of this is seen in the case of the bacterium {Clos- tridium pasteiirianum) which lives in the soil in conjunction with two green algae. The algae supply the bacterium with carbohydrates and it is then able to fix free nitrogen and this combined
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