In one of the sappiest poems ever written -- no pun intended -- Joyce Kilmer couldn't say enough about the loveliness of trees.

Obviously, Kilmer never had a cottonwood in his neighborhood, scattering great wads of that messy stuff into his gutters and birdbaths. Nor, most likely, did he have a crab apple in his front yard, which after one week of splendid blossoms in the spring, occupied itself the rest of the year covering the ground with thousands of rotten little crab apples, for which the only use seems to be a type of jelly that you'll never see on supermarket shelves (for a very good reason).

Sure, it was easy enough for Longfellow to sing the praises of the spreading chestnut tree -- only the village smithy knows what it's like to be constantly brushing nutshells off the back yard anvil.

While it's true that no one would ever want to go without the beauty and shade of trees -- not to mention all the good, edible things many of them bear -- they are a tremendous responsibility when they become part of the homestead.

When dogs and cats and horses ran loose in the wilds millenia ago, they took care of themselves; they got along quite nicely without their balanced meat byproducts and heartworm tablets and distemper shots. But then human beings came along and domesticated the poor creatures, and now they depend on us for even a bowl of fresh water.

This apparently is what has happened to trees. As soon as they end up in somebody's yard they become like pets, requiring constant attendance and faring poorly if they don't get it.

Trees growing in forests never get pruned into shape as young saplings, and they seem to turn our all right; when they get a bad case of cottony maple scale, they get by without a dose of malathion; no one digs around their roots, or feeds them with tree-food spikes, or peels off the shedding bark and carefully dresses the bare spots to keep out bugs. They just tough it out, and when some of them succumb, well, that's part of the old survival-of-the-fittest routine. But when that happens in the back yard, the landscaping is shot, so the average tree becomes a bigger project than a litter of puppies.

Unlike most animal pets, trees don't seem to relish that dependent relationship with the people living nearby. Even though their human caretakers will snatch the first withered branch they see and run to the nearest plant nursery for advice -- which invariably involves purchasing all sorts of expensive "-icides" to do in whatever blight is making the rounds that year -- yard trees seem to go out of their way to make trouble.

They are forever finding ways to fling their leafy branches against windowpanes, or wrap themselves around utility wires, or tangle their roots up in the plumbing pipes. They always drop their "propellers" in the downspout, and it's invariably the one that hangs over the barbecue grill, the patio or the back porch that develops the messiest disease.

For ages philosophers have debated the question, "If a tree falls in the forest and no one is around, does it make a sound?" Instead, they ought to devote their energies to contemplating, "If a tree limb falls in the back yard, whether anyone's around or not, does it ever miss the lawn furniture?"

For all their nuisance value, nothing is more tragic than the loss of a tree, even if it was a particularly troublesome "pet."

A typical suburban family moves into a typical suburban house with a very untypical, gigantic fruit-bearing tree in the middle of the front yard. For years they swear about the shortsightedness of the people who built their home and wonder aloud whatever possessed them to plant the world's biggest cherry tree so that it would hang over the front sidewalk, the porch, the driveway and part of the house.

Of course, it wasn't enormous when it was planted, and the original owners probably never gave a thought to the problem of mashed cherries staining the car, clogging the gutters and getting tracked on the living room carpet. They never realized that the birds would get drunk on the fermenting, overripe cherries and fight over the choicest fruit right outside the bedroom window at dawn during most of July. Or that the roof would be speckled with the pits the birds shake loose.

Really, what could possibly be more irritating than a cherry tree in the front yard?

But then one morning, after a violent storm, it's gone. No more sweet-smelling blossoms in the spring, no more neighborhood cherry-picking outings, no more ceremonies as mother cuts into the last fresh-frozen cherry pie of the year for Thanksgiving dinner dessert.

And how can it ever be replaced? By the time a new one grows big enough to match the one that's fallen, the owner probably will be gone. The new tree will just serve to irritate somebody else, who doesn't realize yet how empty a front yard without a tree -- even an "untrained" one -- can be.