EXCEPT FOR the poison ivy and what happened to poor Bill Broz Eddy, Ranger Mary Kay Belter's attempt to prove that Roosevelt Island is edible was a smashing success.

A dozen people had been picking, nibbling and chewing their way around the island for an hour with Ranger Belter when Master Eddy, age 2, came whimpering along the path rubbing some welts on his chubby right arm and feeling betrayed by Mother Nature.

"Yep, stinging nettles," Belter said as she inspected the affronted appendage. "It will hurt like the devil for about 10 minutes and then it will go away."

The small person was not much mollified, 10 minutes representing a significant fracition of his life, but soon enough he went toodling off up the trail behind brother Matthew, 4.

"That's why I said wear gloces when you gather linging nettles," Belter told the group. "But boiling softens the nettles and leached away the formic acid, and then you've got something like fuzzy spinach, only better, with a more delicate flavor."

"Well, I say it's a weed, and I say the hell with it," a young man muttered. "Let's go back to the mulberries."

the mulberries had been the hit of the "Edible Island" tour, which will be repeated at 11 a.m. each Saturday through the summer, starting from the base of that statue nobody would have dared put up if Teddy Roosevelt were still alive.

Belter, who manifestly enjoys playing Euella Gibbons, had had to do some urging to get people to munch up garlic mustard, gill-over-the-ground and Virginia water leaf, but she had them climbing each others' backs to get to the pink mulberries.

"I like the taste better than either the red mulberry, which is native, or the white, which was imported to feed silkworms," she said.Sharp , everybody nodded. Smack .

I think this pink one must have been a hybrid developed by the Mason family when they farmed the island. They had a big experimental plant nursery not far from here, although we haven't found any of their other bybrids yet."

The island - bridge piers and neo-Druld monument excepted - looks as wild as if the Indians had left just last week, but Belter said the land had been cleared and planted in cotton and tobacco for 101 years and was more or less continuously occupied until well after the Civil War. It is because the woods on the island are young as forests go that there is such a rich mix of plants, she said.

It took a while for some members of the group, conditioned by years of the "don't touch" policy of the National Park Service, to warm up to the idea that they were permitted to forage for federal foliage.

The Park Service ideal still is "take nothing but photographs, leave nothing but footprints," Belter said, but tasting natural edibles is a special case.

"Sampling yes, harvesting no," she said. "You can have what you eat on the spot." Endangered species still are forbidden fruit, but most of them are small and hard to find and taste yuk anyway.

"And if you don't know what it is, don't eat it," Belter said. "Many wild plants are poisonous."

Even when you can find them, wild plants are not always easily come by. They are generally widely scattered and yield small amounts during brief seasons.

"We're not trying to show you how to survive in the woods or live off the land," Belter said. "We just think it adds interest to hikes and walks."

Between the shattering passages of planes to and from National Airport Belter pointed out a beehive doing land office business high in a tulip poplar and a beech tree, putative source of the flavor of Beechnut chewing gum.

"I don't know how they get to the nuts before the squirrels do," she said. "I never have."

On either hand along one section of the trail were fox grapes and burdock whose leaves, stalks and roots yield potherbe, salad crunchies and on asparague-like vegetable. "If you peel off the outer green covering the stems also are great in scrambled eggs."

Nearby was an elderberry bush, which sent one of the tour members into rapture. The flowers make fritters when dipped in thin pancake batter and fried, he said, or can flavors an aromatic white wine; the berries, which ripen in August and are insipid when fresh, make a jelly that puts Concord in the shade and, properly handled, either a fine Port-type wine or a dry red that ages like Bordeaux.

Farther along were a walnut tree (let the husks split by themselves or they'll dye your hands yellow-brown) and a persimmon tree (great jam and bread, but they don't reach ripeness until after a hard frost).

In an open glade near the bridge abutment was a patch of groundberries, also known as running berries, which tasted like blackberries with character. They ran second only to the pink mulberries as the hit of the day, but some of those who went scrabbling after them wished later they had heeded Belter's warning to watch out for the poison ivy.