Soil Inhabitants: Root Fungus

Mycorrhizae

Vital Statistics:
Size:Hyphae (threads) less than 0.01 mm in diameter, extend for many meters (would reach across your bedroom).
Lifespan:Indefinite
Total Fungus Population:up to 20,000 km of hyphae (threads) per square meter (enough to stretch from Seattle to Miami five times).

Natural History:
Unlike plants, fungi have no chloroplasts. They can't make their own food like plants do. Many soil fungi are decomposers. They get energy from the organic matter they eat. But this food supply isn't always reliable.

A very special group of soil fungi have found a guaranteed food supply. They actually grow into the cells of plant roots. There they use sugars that the plant makes. This sounds like it would harm the plant. But the plant also benefits. The fungus extends its hyphae out into the soil beyond the plant's roots. This brings plants extra water and nutrient minerals. The fungus also protects the root from grazing nematodes and other, harmful fungi. In return, plants feed the fungi. This give and take is a true symbiosis. It helps both partners. It's so important to plants that just about every plant in the world has some of these little fungi growing in or around its roots.

In grasslands, the hyphae even connect different kinds of plants. This allows plants to trade the minerals they need to grow. Above ground, a meadow may look like separate plants. Underground, they all belong to a single web of living things.