A moody morning after rain. The rusts poured forth their tentacles again, but after a few hours the tentacles had withered to brown scraps. My oldest son and I decided to retrieve one of them for study. He held a slender branch taut while I cut. The shear blades met in the wet wood with a squeak and a snap; the branch sprang upward, leaving its severed extremity in my son’s hands. He plucked the rust off it avidly.
We watered it in a jar and it revived. Overnight, new tendrils of orange slime pushed their way out through the colandered sphere. It did not need rain, then; any drenching would do.
The next stage of our inquiry took place in a white plastic cup. We had learned that the rust spreads orange spores while it is active. Looking over its gelatinous tentacles, I had no doubt our specimen was alive, but we made the experiment anyway. Into the little white cup it went with a fresh supply of water. In the morning, the water showed orange against the cup, spores coloring the water like a weak dose of Tang.
For a few days my sons were always bringing in bigger, juicier specimens of the rust, poking them with sticks, marveling at them. Then their interest dwindled, and I would find week-old jars of the things on shelves and windowsills, tentacles half dissolved in water, retaining only their color.
It used to be said that a fungus was a sort of defective or degenerate plant, one that lacked chlorophyll and so could not make its own food. It was thus reduced to feeding off the work of others—grubbing in the soil to devour dead animals, fallen leaves, and damp wood.
Biologists know better now. In the last few years, DNA sequencing has revealed strong evidence for all sorts of things we could hardly have suspected. The method is to look for similar strings of DNA, then to analyze them statistically. It is a probability game. All life on earth comes from a common stock; the more dissimilar two life forms are genetically, the longer it has been since they were one. By applying sophisticated mathematical models, geneticists can estimate how long it takes for certain kinds of differences to arise. Then, by comparing these numbers, they can deduce how closely related different kinds of living things are. For instance, human and chimpanzee diverged much later than human and orangutan. Therefore, we are more closely related to chimps than to orangs.
Much of the genetic data has supported traditional Linnaean taxonomy. For example, the prevailing view has long been that the order containing bats is monophyletic—that is to say, bats are all more closely related to each other than they are to anything else. A minority view held that the two major groups of bats actually had separate origins and that animals such as the squirrellike colugo might be more closely related to one type of bat. But the DNA analysis supports the first view—that all bats belong together in one order, with nothing else included.
Other data have cast the whole Linnaean structure into doubt (which is why there is now a competing branch of systematics, called cladistics, that tries to chart relationships in a much more precise, if cumbersome, way). Some of it is quite counterintuitive. We always knew that whales must have evolved from some sort of land mammal, but who would have suspected they still belong in the order Artiodactyla—the even-toed hoofed animals?
As a result, our vision of life has altered; the kingdoms, the very fundaments of Linnaean biology, have had to be shifted about. The fungi have made up their own kingdom since the late 1800s, but we understand now, better than we used to, at least, what they are. Certain organisms that we called fungi because they were slimy and repulsive and because we didn’t know where else to put them—the slime molds, for example—have been exiled from the kingdom. That is not too hard to take, because few of us encounter slime molds with any regularity.
What is harder to take is that these disreputable organisms are our kinfolk. The fungi are not plants at all; they are closer to the animals—to us. We always suspected it, after all. They don’t move the way we do, but some of them, the most visible ones, grow so large and are so complex it almost seems a sign of animal life: the mushroom big as a human fist found on your lawn the day after a rain, for example. I have a vivid childhood memory: something smooth and white nesting in the grass, the size and shape of a chicken egg, hard-boiled and peeled. It was not an egg, however; my dog evinced no interest in it. Something about it made me reluctant to touch it. It had no smell, but somehow it reminded me of dog feces, or perhaps merely the Platonic form of disgust. The weird notion that it was an eyeball crossed my mind, and I went so far as to turn it over with a twig, looking for an iris. It was this operation that revealed its true nature, for it tore open under the stick and revealed, first, the stringy origami I associated with the insides of some mushrooms. The other thing this tearing revealed was the smell, which had hitherto been undetectable: the smell of rotten flesh.
Or maybe their overnight appearances simply seem like a sinister kind of magic. Toadstools, elves.
It is not only plants that live in symbiosis with fungi. We animals do it too. We do not like to think about this, because we have for so long conceived of microbes as unclean things, as invaders. But of course we have always been symbionts, dependent on the microbes in our guts to digest our food. We have colonies of fungus inside us. A so-called yeast infection is really an imbalance. It is not a problem that the yeasts are in the human body—they always are. It’s a problem that their numbers have, because of some teetering of the pH level, exceeded their usual bounds. It is a natural thing to share our bodies with them, and with all manner of other organisms. As a tree is not simply a tree, we are not simply what we think we are.
Which is not to exonerate them all. Plenty of fungi are pure parasites, and these have invaded almost every form of life. There are specialized fungal parasites of single-celled diatoms and even of other fungi, and some of these cause serious harm. The rust on my red cedar tree was bad for it; it must have been even worse for the apple trees in the neighborhood, for the leaves of the apple are slowly pierced through by the rust, until spore-shooting orange masts sprout from their undersides. The fruit of the apple, too, may be ruined, its hide marred by soft brown patches.
So, too, with the human form. There are fungi to make the feet and the testicles itch, fungi to discolor and deform the fingernails. And there are neighborly fungi content to live within us unobserved, but which will blossom, in the case of a ruined immune system, into devouring sores inside and out. It is a common enough way for people with AIDS to die.
Two years have passed since the last time our red cedar was dazzling in its orange jewelry. The next year we waited in vain for another blooming of that odd fungus life. We had trimmed the galls off where we could reach, hoping to save the tree, but it wasn’t our earthbound efforts that drove them away. We could still see dozens of them higher up, dry and drab, refusing to bloom. This is the way of the rust. It dies on apple trees, but on red cedar it can persist, give its life to the wind, or leave its old self to rot.
Our tree grows shaggier, more patched with vanilla and auburn. Within the greenery that remains I can reach dozens of lifeless branches. A good yank is sure to be rewarded with the crack of dead wood. The whole tree is ugly now, truth to tell. It reminds me of nothing so much as the shaggy head of a neglected old man.
Not that I neglect the tree. I prune; I am doing what I can to save its life.