The National Gallery of Art today paid $4.07 million -- a record auction price for an American painting -- for Rembrandt Peale's portrait of "Rubens Peale with a Geranium."

Income from a new $55 million gallery fund was used to buy the picture at Sotheby's auction house.

It was consigned by 80-year-old Pauline E. Woolworth, widow of Norman B. Woolworth, whose father founded the five-and-dime store chain. Bids started at $1.5 million and accelerated in $100,000 increments. The sale was completed in less than 90 seconds.

Though the winning bid was $3.7 million, Sotheby's extracts a 10 percent "buyer's premium" from successful bidders.

J. Carter Brown, the National Gallery's director, was present in the salesroom at Sotheby's, though Lawrence A. Fleischman of Kennedy Galleries, a leading Manhattan dealer, did the bidding on the museum's behalf. When the auctioneer identified the new owner as the National Gallery, the standing-room-only crowd burst into applause.

Brown then turned around in his center-aisle seat and quipped, "Any donations will be gratefully received."

The picture, which celebrates the science of horticulture as much as the art of portraiture, was painted in 1801 by 23-year-old Rembrandt Peale. He portrayed his younger brother, Rubens, in a no-frills brown suit, his right hand touching the soil in a terra-cotta pot containing his prized geranium. The painting, slightly more than two feet high, is half portrait and half still life. The blooming plant takes up as much room as the sitter, whose most outstanding characteristic is the pair of spectacles perched upon his nose. Their oval rims punctuate his gaze, their lenses cast luminous refractions on his smooth cheeks.

"This is such a quintessentially American picture," Brown said later. "It is perhaps the first American portrait in a totally American style. It represents our pragmatism and new-found pride in our can-do capabilities."

The purchase is the first made by the gallery with the income from its new Patrons' Permanent Fund. That fund, the fruit of a nationwide fund-raising campaign ending this month, now exceeds $55 million. Although its principal will not be touched, its income has been set aside for major acquisitions.

The previous auction record for an American painting was held by Frederick Edwin Church's mural-sized "Icebergs," painted in 1861, which sold in 1979 for $2.75 million to an anonymous bidder.

Samuel F.B. Morse's "Gallery of the Louvre" (1832) sold for even more, $3.25 million, in 1982, but that picture was purchased privately from Syracuse University by Ambassador Daniel Terra for his Illinois museum. The world auction record for a painting is the $10.4 million spent last April at Christie's salesroom in London by the Getty Museum of Malibu, Calif., for Andrea Mantegna's "Adoration of the Magi."

Minutes after the sale, Brown telephoned his deputy director, John Wilmerding, in Washington to relay the good news.

When asked if he had been prepared to go home empty-handed, Brown replied, "Yes, we were perfectly resigned to the fact that the bidding might have gotten wild. You get some of these private collectors going, and they become very excited."

Sotheby's had accurately predicted that the painting would fetch $3 million to $4 million. Two private collectors competed for the picture but dropped out when the bidding reached $3.6 million.

The portrait, said Brown, "is a gift to the nation from all the people who have contributed to the Patrons' Permanent Fund -- including many Washingtonians who gave an overwhelming response last spring when we canvassed for this permanent endowment for art acquisitions."

Wilmerding, a specialist in American art, said, "You could define the Peale as the first great American portrait -- with emphasis on 'American.' Unlike most of John Singleton Copley's portraits -- with their stiff, formal poses derived from English art -- this picture, with its casualness and informality and its combination of art and science, suggests an American idiom."

Both 23-year-old Rembrandt Peale and his brother Rubens were sons of Charles Willson Peale (1741-1827), himself an artist-scientist who established the nation's first museum. He had 17 children. Those from his first marriage he named after such painters as Rembrandt, Rubens, Raphaelle and Titian. Those from his second, were named for scientists, such as Benjamin Franklin and Linnaeus.

The paintings of Rembrandt Peale (1768-1860) were not always widely praised. Stung by criticism of one of his pictures in 1812, he temporarily abandoned painting and moved to Baltimore, where he built the Peale Museum and established the first illuminating gasworks in that city. Returning to painting in 1820, he produced his most famous canvas -- that is, until yesterday -- the 11-by-23 foot "The Court of Death." That picture earned him $8,000 in admission fees during its first year of public exhibition. It is now at the Detroit Institute of Arts.

His portrait of his brother has been seen often in Washington. Most recently it was included in "A New World: Masterpieces of American Painting, 1760-1910," a traveling exhibit shown at the Corcoran Gallery of Art. It also was displayed at the National Gallery in the Bicentennial exhibition "The Eye of Thomas Jefferson" and at the Baltimore Museum of Art in "Painters of the Humble Truth: Masterpieces of American Still Life, 1801-1930," a show organized by William H. Gerdts in 1981.

The canvas, shipped to Washington following the sale, will go on view early next week in the gallery's West Building.

In addition to the Peale sale, a Georgia O'Keeffe work, "White Rose, New Mexico," was sold to an anonymous buyer for $1,265,000, a Sotheby's spokesman said. It was the highest sum ever paid for an O'Keeffe painting.