WASHINGTON (AP) _ There's a place in American culture for the marshmallow, somewhere between bittersweet chocolate and warm graham crackers, the Smithsonian Institution says.

The Third Annual Smithsonian Conference on Stuff, held Friday, wasn't hard to swallow, oozing from serious botany to curious history and back again. And its date - April Fool's Day - was no coincidence.

The rigid layers of the Moon Pie were likened to the stratified social structure of the South, and contrasted with the democratic mass of the Goo Goo Cluster.

Steven Turner of the Smithsonian's Division of Physical Sciences wondered whether there is any link between very old marshmallows and styrofoam packing peanuts.

Marshmallows' minor mark on music was discussed by Dwight Bowers of the Smithsonian, who recalled Dinah Shore's 1951 recording ''Marshmallow Moon'' including the lyric: ''There's a marshmallow m-o-o-o-n on a velvet sky tonight.''

Marshmallow mashed into velvet: not Bowers' idea of a romantic image.

''It's a sticky subject'' admitted Richard Ahlborn, who opened the conference.

Katherine Ott of the Smithsonian's Division of Medical Sciences said marshmallows have even found a place in the healing arts.

Originally one of the five humors of the body identified by the ancient Greek physician Galen - along with lymph, blood, bile and beer - it was later dropped after a lawsuit by the Good Humor man, she joked.

Modern experiments, Ott went on, have suggested the use of marshmallows rather than silicone in implants. Marshmallows don't migrate around the body, she said, although there is a tendency to gravitate toward campfires.

Gary Aronsen of the Museum of Natural History took up the origins of the marshmallow (Staypufii alabastus) which he traced through the fossils found in a petrified marshmallow bed in the West.

The tiny pygmy marshmallow was first sighted in 1832, said Aronsen, who sought to determine whether the large and small versions are the same species.

Both types of marshmallow have evolved under intense predation by humans, he observed.

Momentarily losing his train of thought to comment: ''I can't believe I'm doing this,'' the scientist regained composure and explained he was unable to complete his research - his dog ate the subjects.

''Most of us never kissed a girl until we had first pressed a marshmallow to her lips,'' said folklorist Thomas M. Kirlin in a lecture entitled: ''The Marshmallow in Midwestern Male Courtship Rituals.''

Kirlin recalled his efforts as a 14-year-old to enchant a girl by toasting a marshmallow over a bonfire - losing several into the flames and singeing his fingers before succeeding.

Finally, ''we feasted on marshmallows, the magic of courtship worked, we kissed, it lasted about a week. So, you see, I've been burnt by the modest marshmallow,'' he concluded.

Turning to today's information society, John Fleckner and Thomas Bickley told of a visit to cybermallow, a trip through the Internet marsh.

Searching the worldwide computer network for marshmallow references, they discovered an 1806 treatise on using marshmallow mucilage to treat kidney stones, an experimental paper on the heat released by burning marshmallows, a news story about football fans pelting players with frozen marshmallows and hundreds more.

Camy Clough went to the source for her experiment, offering school children a choice of marshmallows to taste test.

''There was a gender difference in marshmallows,'' she found, with boys preferring big ones and girls the miniatures. Offered a choice of colors, boys went for green while girls liked orange and pink.

For the record, the high-sugar marshmallow plant was once the source of the confection. The plant root produced mucilage for texture. Modern marshmallows, however, are made from corn syrup, gelatin sugar and water, said Beth Richwine of the National Museum of American History.

The Smithsonian's conferences on stuff are held each year on April Fool's Day. Previous years' sessions have focused on Jell-O and peanut butter.