When American millionaires bought paintings by Piero di Cosimo in the late 19th century, almost all the works were attributed to other Italian Renaissance artists. Piero, a painter of Florence during its golden age, was simply regarded as too obscure to produce such masterful works.

It took many decades for Piero to emerge even partly from such shadows. Not until 1938 did the private Schaeffer Galleries in New York mount a small show of seven paintings all correctly attributed to him. But there was no other Piero exhibition anywhere in the world in the 20th century.

Art historians, however, continued to study the fascinating case of Piero, discovering more of his works, many of the highest quality. The evidence mounted that the city of Florence, which could boast of Leonardo, Botticelli, Filippino Lippi and others during the Renaissance, also had another — though unheralded — master.

A decade or so ago, specialists realized the time had come to introduce the new Piero to the public. “As a curator you see what needs to be done,” said Gretchen A. Hirschauer, the associate curator of Italian and Spanish paintings at the National Gallery of Art. She and her co-curator, Dennis Geronimus of New York University, persuaded the National Gallery of Art in Washington to mount a show. When they discovered that the Uffizi Gallery of Florence was also contemplating a Piero show, they formed a partnership with the Italian museum.

The exhibition, “Piero di Cosimo: The Poetry of Painting in Renaissance Florence,” opened Feb. 1. After closing on May 3, the bulk of the show will go to the Uffizi Gallery from June 23 to Sept. 27.

For the public, the show is an unusual experience: a chance to attend a coming-out party for Piero and judge whether he should stand alongside the other Florentines. And there is more than a sampling to make a judgment. (“Are we ready for a five-hundred-and-fifty-three-year-old overnight sensation?” asked the New Yorker’s smitten art critic, Peter Schjeldahl).

Hirschauer estimated that there are fewer than 60 Piero paintings left, and the exhibition is showing 44 of them, on loan from museums and collections in the United States, Canada, Brazil, and from across Europe. Gallery visitors will find out far more about the work of Piero than his life because researchers have failed to uncover much about him beyond his reputation for strangeness.

Although the curators refuse to enter the game of sizing Piero up against each of his contemporaries, Hirschauer insisted that “he falls into the ranks of the most successful painters of his generation.” Piero’s calling card was a penchant for painting narratives — nonbiblical stories taken from mythology, folklore and antique tales. “Botticelli was the only rival,” Hirschauer said, “and Botticelli did not have all Piero’s delightful detail in his narratives.”

A good example is Piero’s “Liberation of Andromeda,” a wood panel painted for a private palace between 1510 and 1513 and now owned by the Uffizi. The painter based his story on verses in Ovid’s “Metamorphoses,” itself based on a Greek myth.

According to Ovid, the gods, angry at the royal family of Ethiopia, dispatch a sea monster to destroy their kingdom. The king and queen hope to satisfy the monster by sacrificing their daughter, Andromeda, to him. Perseus flies to her rescue, slays the monster and wins Andromeda as his bride. The whole story is on the panel — Andromeda in anguish and terror, Perseus flitting across the sky and hacking at the monster with his sword, and then the happy finale.

Modern audiences, their tolerance for monsters expanded by Maurice Sendak and King Kong, may find the dying sea monster somewhat less than ferocious, but there is no doubt that the potential victims painted by Piero are writhing in real fear.

Menace and lust dominate a pair of bacchanals painted in 1500 for the bedrooms of a private palace: “The Discovery of Honey” and “The Misfortunes of Silenus.” Again using Ovid as his source, Piero has peopled each painting with Dionysius, the god of winemaking; his companion Silenus, the god of drunkenness; a host of goat-legged satryrs, and humans intent on pleasure. One satyr wears a cod piece that looks like the live head of a sharp-featured animal.

Although Pan is handing out aphrodisiac onions and Dionysius, wearing nothing but a thin shawl, appears aroused, the bacchanals have not yet begun. Infrared studies have revealed that the paintings had a few more bawdy touches that were removed by Piero himself, perhaps at the request of the buyer.

Portraits and church art were the main work of the painters of Florence during the Italian Renaissance, and Piero won his fair share of commissions for the more popular genres. His double portrait of the architect Giuliano da Sangallo and his father, loaned to the exhibition by the Rijksmuseum in Amsterdam, was so remarkable, according to Hirschauer, that it was at first attributed to Albrecht Durer, the great German painter of the Northern Renaissance. The portraits were painted from 1482 to 1483 when Piero was barely 20 years old.

His biblical work is infused with lively portraits and extraordinary detail. Some works are familiar. “The Visitation with Saint Nicholas and Saint Anthony Abbot” has been in the Renaissance collection of the National Gallery of Art since 1939. Piero painted it in 1489 and 1499 for the Church of Santo Spirito in Florence while the building was under a renovation designed by Giuliano de Sangallo, the architect in the double portrait.

Piero was born in Florence in 1462, later than most of the best-known painters of an era that Hirschauer calls “an unparalleled half-century in art.” Botticelli was 22 years older than Piero, and Leonardo was 10 years older. Piero’s father had nothing to do with art but was either a blacksmith or a toolmaker.

He was apprenticed to the painter Cosimo Rosselli in the 1470s and took the master’s first name as his own surname when he left the workshop, calling himself Piero di Cosimo. But like a good number of other artists, he became known by his first name alone.

He first attracted attention by designing floats for the city’s Carnival parades and soon received commissions to provide altar paintings in churches and narrative paintings for private palaces.

There is little documentation about him except for several pages written by Giorgio Vasari in his 1550 book, “Lives of the Most Excellent Painters, Sculptors and Architects.” Vasari had never met Piero, but that did not prevent him from depicting the painter in colorful and demeaning prose.

Vasari wrote that Piero, who was strange, “knew no pleasure save that of going off by himself with his thoughts, letting his fancy roam and building castles in the air.” “Men could see the strangeness of his brain,” Vasari went on, insisting that Piero would never have his rooms cleaned or his garden kept in order.

Piero, according to Vasari, “could not bear the crying of babies, the coughing of men, the sound of bells, and the chanting of friars.” “He was rather held to be a madman,” Vasari concluded, “although in the end he did no harm save to himself alone.”

Art historians do not know what to make of these characterizations but have no evidence to refute them. There is an assumption that Vasari is guilty of some exaggeration because it would seem odd for the Florence establishment to lavish so many church commissions on an artist the townspeople thought was mad.

Piero died in 1522, probably a victim of the plague.