OUR cosmos grew to eight feet last year, and I'm beginning to feel botanically empowered, maybe a little like those urban or innercity planters who are greening their neighborhoods. I think of BUG (Boston Urban Gardeners at the Community Farm Inc.), which has been helping residents turn vacant lots into gardens since 1976. Or West Roxbury High School in West Roxbury, Mass., where students study animals and plants as ``bio-indicators'' reflecting the health of their environment: For example, varieties of lichens, ranging from ``those most tolerant of air pollution to those least tolerant.''
Not that I'm in their league, though I did loosen the soil when my wife Joan first put in the cosmos seeds. I'm just one of those city folks following Ralph Waldo Emerson to the feet of Linnaeus, a fellow Swede who Emerson said ``makes botany the most alluring of studies, and wins it from the farmer and the herb-woman.''
Linnaeus, a.k.a. Karl von Linne, was the brilliant 18th-century classifier of genuses and species who calculated that an annual plant like our cosmos, if uninterrupted, would produce a million plants in 20 years. All it would have to do is produce two seeds, and their two seedlings produce two each, and so on. Darwin cited Linnaeus to argue that ``there is no exception to the rule that every organic being naturally increases at so high a rate that, if not destroyed, the earth would soon be covered by the progeny of a single pair.''
I suppose the earth could do worse than be covered by cosmos, each flower a small sun with colorful rays. Ours have done well but not that well. Still, even a slight brush with horticultural greatness can make stamens and pistils more interesting than they used to be.
So on a trip to Pittsburgh, I seek out the meticulous paintings and drawings by today's artistic descendants of Audubon in the Hunt Institute for Botanical Documentation at Carnegie-Mellon University. The diversity of pictorial styles is striking, and sometimes the plants appear in decay and disarray instead of in traditional textbook perfection.
Just like at home. And, back in Cambridge, I find a store selling Hunt Institute greeting cards of plants and flowers, though not the ravaged ones. It's comforting to see that, even in 1825, Antoine Chazal painted at least an insect or two on his magnificent bouquet.
By comparison with the stately cosmos, our nasturtiums seem like rowdy groundlings. I've just discovered they're the same plant that Spanish explorers found among flower-loving Peruvians in the 16th century - and brought home along with 11 million pieces of silver in the ``bullion fleet'' of 1587.
Please don't eat the daisies. But do eat the nasturtiums, as we invite guests who pick their way warily through the house salad. This customarily includes a bit of just about everything in the garden. It's possible to have too much arugula.
Purslane is another matter. We don't harvest it yet. But our farmer son and daughter-in-law served it the last time we visited them, and I asked for more. It grows as a weed but is being sold more and more in stores, they told us - a tasty, nutritious contender for the spinach market.
The Oxford dictionary says purslane (Portulaca oleracea) was ``formerly'' much used in salads. A Macmillan encyclopedia calls it a ``small succulent annual herb, native of tropical Asia.'' Webster describes ``a fleshy-leaved trailing plant with tiny yellow flowers that is a common troublesome weed but is sometimes eaten as a potherb or in salads.''
I look out for purslane as I go about the tasks permitted to me on the farm. Dad gets to sickle the rough grasses the horse-drawn mower can't reach under the deer fence. I am instructed in the deceptive resemblance between ragweed and the tops of the carrots it infiltrates as if by design. After picking basil and garlic for a while, I smell like pesto. After tying up long rows of tomatoes, I have yet another fragrance added. When I wash my hands, the water turns green.
This way lies chlorophyll overload. Probably a little botany is a dangerous thing. Stop me before I double-dig the cucumbers again. I could become surreal, like Magritte's portrait of a man in suit, tie, and derby with a huge green apple obscuring his nose, mouth, and most of his eyes. It takes a William Blake to see ``...a world in a grain of sand/ And a heaven in a wild flower.'' But I did see the cosmos in our garden.