by Peter Lesica
Broadcast 7.6 & 7.7.2014
The other day my friend Suzanne called me on the phone. “You’ve got to come up Pattee Canyon with me. I’ve just seen the strangest plant. It looks like a primitive asparagus, but it’s orangish.” I thought I knew what it was, and when we got there I found I was right. It was a developing pinedrops plant.
Pinedrops are found only near conifers, especially pines. When they begin growth in early July it is a golden spear-like shoot. When mature it’s sticky and a deep reddish-brown with nodding flowers spiralling at the top of the one- to two-foot stem. Thousands of tiny seeds are produced in the pumpkin-shaped fruits in late summer. The most striking features of this plant are that it has no leaves and isn’t green. If it isn’t green it’s not photosynthetic, so how does it grow?
Pinedrops is a member of the heath family. Other members of this family, such as Indian pipe and pinesap, also lack leaves and chlorophyll. These plants are often called saprophytes, but in fact they are not. True saprophytes depend on dead and decaying vegetation for food, while pinedrops and its relatives do something different. These mycotrophic achlorophyllous plants obtain their carbohydrates from mycorrhizal fungi which originally obtained it from a tree!
All of our conifers form a symbiotic partnership with certain soil fungi. The fungus helps the tree obtain mineral nutrients and receives energy-rich carbohydrates in exchange. Pinedrops insinuates itself into this partnership by taking carbohydrates from the fungus. Radioactive carbon compounds injected into trees appear in nearby pinedrops a short time later. However, pinedrops is not a freeloader; it provides the mycorrhizal fungus with a growth-stimulating substance, and radioactive phosphorus injected into pinedrops appears later in adjacent trees. So this is why pinedrops are found only near conifers. In this three-way mutualism everybody wins.
Pinedrops can be found in many of our low-elevation forests and seem to be more common in wet years. It is conspicuous while in flower, but the tall darkened stems with their jingle bell-like fruits are still apparent in the fall and winter.
These simple-appearing plants give testimony to the complex web of life going on below ground.
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