One of the greatest treasures of the capital is the towpath along the canal by the Potomac. The heavily trafficked paths are, of course, sacred to horses, joggers and similar beasts, but just a few feet off the path you will see great things.

It would be a help, if you wander along with no great purpose in mind, to carry a good-sized sack and fill it with empty cans and bottles that you find. You have to remember that in our free society a number of natural-born slobs live. It's not their fault that they toss beer cans about; it's the way they are, but sometimes it's no real trouble to carry out a bag of their trash till you find a trash bin.

A few days ago I toured the path from Hains Point to Great Falls with John Hoke. As everybody knows, or should, he is an authority on the sloths of Suriname, the turtles and toads of the capital, and the construction of terrariums.

I met him at his office on the point, where he works with National Capital Parks in the resource management department. He has an electric cart that holds two people. He deplores windshields and tops, and of course we chose a fine raw cloudy day. Like me, he loathes the cold but bears up well in an amazing wool coat he got in London, with a cape attached.

Once the commissary opened we supplied the expedition with liverwurst and salami sandwiches and a jug of water. Leaving base camp at 9:30 we made the hazardous crossing of Ohio Drive where that big bed of pansies is at about 9:33. In seven minutes we were on the towpath in Georgetown.

Hoke puffs cigars, speaks into the wind and veers to the left a good bit to hurl the cart down steep banks to check on some tunnel or other along the way. A good bit that he says cannot therefore be heard but no matter.

Of all men living he best knows the haunts of the several turtles -- the painted, the sliders, the woods and the box turtles. He is also unsurpassed in knowledge of the haunts and the timetables of toads. It is perhaps too bad that in our daylong trek we saw no snake, no frog, no toad, no turtle. It is still true that Hoke is tops for a tour of toad viewing. In his own pools at home the toads are mating, but of the millions along the ponds and backwaters off the towpath, not one condescended to be viewed.

We stopped altogether at maybe 50 ponds, pools and notable puddles. I showed him my own favorite large puddle that dries up in the summer but stays dampish and is a haven for clouds of butterflies that sip the mud. Not a single butterfly, of course, because I wanted to show them off.

There are places where three or four kinds of lovely green moss grow together. In some places the trunks of even saplings are covered with delicate lichens.

Sometimes we saw a single Virginia bluebell in a rocket of bloom -- never in those solid stretches, which is their natural way to grow. Perhaps too many visitors have dug up a sampling in defiance of law.

We walked over spring beauties, those tiny pink upward-facing cups that turn white, as dense as a lawn. I stopped for a closer look at a clump of wild white phlox, as well as the commoner (and equally beautiful) blue kind.

Little pipsissewas are up and squirrel corn is in flower. Whole banks of polypodies are lush and fresh, though in summer when the trees are in verdure you don't see them.

Few people, I think, have vanished forever into the woods along the towpath, though you are certain to get lost, so allow some time. Next week, surely, the melodious songsters (toads) will be out in force though on chilly days you have to make do with mockingbirds.

Needless to say the penalties for removing plants or animals is terrible. As I recall, they drop you in boiling oil, but even if they didn't, it is so small-minded to steal something from a public park that nobody you know would dream of doing it. Including you, I trust.

Hoke pushed aside briars -- we got out of the cart every few minutes to roam about -- like Sherlock Holmes approaching Baskerville Manor. He is one of the few humans I ever knew who love cat brier. The shadblow is out, sometimes hanging in gaunt contorted branches over the water, sometimes deep in the woods.

It is very beautiful. It is very accessible. It is a treasure such as they do not know in New York or London. We owe it to ourselves to take a day off, or half a day, or an hour before it gets dark, to walk in those woods full of little pools and water clover. You don't have to know the name of anything -- just take time to look closely. Salami, by the way, does better than liverwurst.