A COUPLE OF years ago I was admiring the boneset (Eupatorium) with white puffs of small flowers in clusters -- indeed, it is often called hardy white ageratum -- and resolved to save the seed.

I scattered it here and there, a mistake, of course. It came up all over the place, back of the scarlet azaleas, on top of the tectorum irises, over the roots of the Carolina jasmine.

It is in bloom, handsome as ever. It is the sort of plant that when you see it, waist to shoulder high, you say, "Now that is a very good thing." Blooms heavily, grows like a weed, comes in late September (always an advantage in flowers, surely, since there is not much blooming then), has no pests, needs no staking.

It is not, however, what you want. However good-looking it is, it's weedy. Along an alley, it's fine. Along a country fence row, it's fine. In a town garden, it is not so fine. It takes too much space for its two or three weeks of white bloom. Still, I will say this for it, no matter what the weather in July and August, it always looks green and flourishing. Because it is flourishing, no doubt.

Also blooming now is the magenta phlox, the one that upsets delicate stomachs and which I substantially admire. For one thing, it does not seem to get eelworm at the root, an affliction of many garden phlox. And it will grow in unweeded corners. It is, needless to say, rather a weed. In spring and summer when I notice it, I pull it out where it is bothersome. Always I manage to leave enough to produce a few spots of color.

Some of the late-planted gladiolus are in their last bloom, and, thanks to hurricanes, have flopped about. I discovered three stalks on the ground, a real feast for the slugs who love to eat any flower that keels over, but I pulled off what remained of the slugfest and still had a few florets at the tip of the stalks.

They were a nice orange-apricot color, and I cut them with a few sprigs of the white-striped Chinese grass ( Miscanthus sinensis variegatus ) and the magenta phlox and a few roses, "Sutter's Gold' and a fat mound of the sedum 'Autumn Joy.' In a silver vase, they looked fine.

At shows I sometimes see great classes devoted to flower arrangements. No doubt they are a good thing, and keep many people out of the mischief into which (judging by the arrangements) they would certainly run.

Furthermore, as a tolerant sort of fellow, I see no harm in self expression through flower arrangement, and I know that many women greatly enjoy collecting junk in which to display their art.

It also is amusing to hear the lofty tone of speaking that so many of them affect in discussing their arrangements. You gather that their profound souls, together with the direct advice of God, have accounted for the little platter of brushwood displayed.

And why not. I do think it fitting to observe, though, that the results are more often odd than beautiful. Art at its most self-conscious is usually bathos at its worst, and this is well seen in the average assortment of flower arrangements.

An artless vase of field flowers or a jug of lilies have the merit of not falling on their face because not much, in the way of high art, was attempted to begin with. Surely it is a fine thing for people to say, "Yes, but I want to express something more than the fairly obvious and apparent beauty of the flowers themselves."

Very good. But a stone sculpture cannot ignore the stone it is made of, and no art can very well reach the heights without a perfect sympathy by the artisan for his medium. Plants and flowers, if I may point out the neglected obvious, are not lines or masses, they are not calligraphy or sculpture or painting. They are plants.

The minute they start being thought of as "elements of design" or materials" for this and that, they start being used poorly.

They have a life of their own. The minute this is forgotten, and the minute they are used for ulterior purposes, as you might say, at that minute they start looking wrong.

Simplicity is no answer, by the way. I saw a vast arrangement of cherry blossoms, involving perhaps a third of a good-sized cherry tree, at some Japanese lecture a while back, and it looked awful. It was in scale with its vasy surroundings, I concede that, but its very size worked against it. It is rather like thinking a basket of small cats is charming, and deciding (for the decoration of a large hall) that a 25-foot basket could accommodate, let's see now, 4,250 kittens.

No, art is complex. There is no refuge in "simplicity."

A long and full acquaintance with plants and flowers is a good beginning for the flower arranger. A certain humility or reverence for the medium will go far in the avoiding of bombast and folly. Needless to say, just as there are El Grecos that one may not like, there are many examples of good work that one may not like. It is hardly necessary for us to admire everything that is dandy.

But two points: The arrangements seen at flower show would, in general, look better, or less precious, or less lugubrious, or less trite, or less infuriating, if fewer gew-gaws in the ways of porcelain ornaments, brass mustard pots, Sevres spittons, iron hinges, and dented enameled automobile fenders were used to "point up" the "theme" of the arrangement.

If you can't say it with flowers, then don't use flowers to say it.

The second point: It is more than an error, it is a sin, to get so caught up in the theories and furbelows or some pastime like flower arranging that newcomers to the field (and may they be spared from its more foolish excesses forever) are intimidated and clobbered. A thing that happens.

It sometimes happens in America that many people admire junk and make it, finding great support among the others who also like junk. In this way, they go from peak to peak of support and applause and soon forget what they knew when they started, that it was just harmless junk. All of a sudden it becomes "art" and the fat's in the fire, the horse is driving the chariot (rarely wondering why it does not move) and the patience of reasonable people is strained.

Speaking of strained patience, there is a giant plastic basket at the Smithsonian Institution's Victorian Garden, which I commend to everyone to go see. If there is one aspect of it (it is stuffed with plants) that you admire, you should be born again and start over. If it is thought amusing as a period piece, or a nice touch to the somewhat puerile design of the garden itself, or a festive little exuberance like the Cathedral of Chartres in miniature, made of toothpicks, then possible you can compliment yourself on your sense of humor.

But quite possibly there is something rather wrong with admiring it. As usual, the main trouble with it is that it uses the medium of plants to do what another medium (pastry, hallucinogens, among them) would do better and less offensively.

Through blessed contrast, go a few steps further to admire the great borders of cannas against the Smithsonian's Arts and Industries Building on Independence Avenue. These are not merely good-looking, they are beautiful and cannot be improved upon. The Smithsonain, to whom education is everything, has once more shown us in a small space both the depths of triteness, coarseness and vulgarity, and the plateaus, even the heights of taste and judgment, and all of this between the cruddy basket and the noble borders.