Excerpts from Jim Conrad's
from the August 14, 2005 Newsletter issued from the Sierra Nevada foothills
somewhat east of Placerville, California, USA
After you've been paying attention to wildflowers for a while you recognize that there's a whole subset of parasitic and saprophytic wildflower species containing no chlorophyll and thus are not green and bear no normal leaes. Beechdrops, Squawroot, Indian Pipe, Coralroot, Broom-rape... Besides the lack of greenness and normal leaves, another feature common to all those species is their low stature, seldom over a foot high.
Upslope in deep pine forest there's a leafless, brown wildflower blooming now that breaks the not-over-a- foot generality. It's Pinedrops, PTEROSPORA ANDROMEDEA, a member of the Heath or Azalea Family. I've been finding their lusty, slender flower spikes up to four feet tall. You can see such a spike here.
Many books state that Pinedrops are saprophytes -- plants deriving their nutrients from decaying organic matter. Recent studies indicate that Pinedrops are actually special kinds of parasites requiring the presence of three distinct species. First there's the Pinedrops. Second is a "host" plant photosynthesizing its food the usual way. Often the host is a conifer or popular tree. Most Pinedrops I find here grow beneath Pondorosa Pines. The third species required for the Pinedrops' special situation is a mycorrhizal fungus, probably of the genus RHIZOPOGON, which connects the roots of the two previous species providing a means by which photosynthesized material from the host is transferred to the Pinedrops. Since Pinedrops survive on food photosynthesized by a pine who doesn't appear to benefit from the association, Pinedrops are parasites, not saprophytes. This special form of parasitism is often referred to as ectoparasitism.
When you find such complex relationships among organisms you're struck by how fragile ecosystems can be. Most mycorrhizal fungi are rather fastidious about the kind of soil they grow in so if the soil isn't just right there's no mycorrhizal fungus and therefore no Pinedrops. I don't find Pinedrops in areas that have been clear-cut with resulting extensive soil erosion, and now it's clear why this is the case.
When some people see the even-aged, monocultured pine plantations growing where forest used to be they claim that they are seeing forests returning after clear- cutting. They are simply ignoring all evidence beyond the fact that at least one species of pine can survive on that abused soil. As I wrote earlier, ecologically, the even-aged forest returning to these clear-cut areas has more in common with desert-like cornfields than healthy forests.
And they sure don't have Pinedrops.