7/6/14 & 7/7/14: This week on Fieldnotes: "Pinedrops," by Peter Lesica, read by Anne Garde.
"All of our conifers form a symbiotic partnership with certain soil fungi. The fungus helps the tree get minerals and in return receives energy-rich carbohydrates. Pinedrops (Pterospora andromedea) insinuates itself into this partnership by taking some of those carbohydrates from the fungus.
However, pinedrops is not a freeloader; it passes along a growth stimulant to the mycorrhizal fungus. Radioactive phosphorus injected into pinedrops appears later in adjacent trees. That's why pinedrops is found only near conifers. In this three-way mutualism, everybody wins."