Hunter Drohojowska-Philp, Full Bloom: The Art and Life of Georgia OKeeffe, 628 pp., Norton, $35.

Over a long life -- one that literally spanned the 20th century -- Georgia OKeeffe (1887-1986) went from schoolmarm to siren to high-desert sage. In her exhaustive new biography, Full Bloom, Hunter Drohojowska-Philp painstakingly traces that journey. While the myth of OKeeffe depicts her as an artist of single-minded ambition whose innate talent allowed her to glide to iconic status, this biography tracks her emotional and professional travails, the various hurdles in her path and how she overcame them.

The biography divides OKeeffes life into three main sections, which are given New Age-style titles -- "Beginning," "Becoming" and "Being." The early years include the artists childhood in Sun Prairie, Wisc., her fathers financial misfortunes, and her struggles to find work as an art teacher. Though a Midwesterner -- she was at a school in Texas before coming East -- she had explored the artistic possibilities of New York. In 1916, a friend showed some of her drawings to Alfred Stieglitz, the famed photographer who operated the pioneering 291 gallery on Fifth Avenue, mounting some of the first modernist art exhibitions in the U.S.

It was then that Stieglitz issued the memorable phrase, "Finally, a woman on paper." Married, the father of a young daughter, Stieglitz became OKeeffes mentor and patron, exhibiting her work at his gallery from 1917 through the 1920s. He was 23 years her senior.

Arguably, OKeeffe came to public notice as Steiglitzs muse. She was first his model -- often posing bare-chested in front of her own paintings -- and then his mistress. In the blooming heat of their relationship, which probably began in 1918, he took some 200 photographs of the heavy-lidded, raw-boned beauty, many of them frankly erotic. Years later, these pictures would haunt her.

Eventually Stieglitz left his wife and child, moving in with his young protg. The major casualty of the liaison -- the two were married in 1924, and the legal union lasted until Stieglitz death in 1948 -- was the photographers daughter, who promptly lost her mind, was institutionalized and never fully recovered. The honeymoon didnt last. As OKeeffes reputation as an artist grew, Stieglitz interest waned. Even early in the marriage, he was given to flirting with (and photographing) other women, such as photographer Paul Strands wife Rebecca. In 1927, Stieglitz secretly took up with Dorothy Norman, a pretty, married socialite in her early 20s who had wandered rather naively into his gallery one day, looking for insights into modern art.

Even after she learned of Stieglitz relationship with Norman, OKeeffe put up with the affair for several years. For his part, Stieglitz referred to his new lover as a "Child-Woman," just as hed once done with OKeeffe, and he photographed Norman in the nude in the late 1920s, telling her, as he had OKeeffe, "Each time I photograph I make love."

Stiegliz photos of Norman proved fateful. In 1932, Norman helped Stieglitz to put on a 40-year retrospective of his work. "None of Stieglitzs photographs were as stunning to the public as the portraits of Norman presented alongside those of OKeeffe," Drohojowska-Philp tells us. "Pictures of the doe-eyed young socialite were viewed as a deliberate rejection of OKeeffe."

In 1933, OKeeffe had a mental breakdown, and was hospitalized for three months. Eventually, the collapse of her marriage to Stieglitz proved as significant as their early partnership, as it "drove OKeeffe to redefine herself, not as he saw her but as she saw herself, in New Mexico."

Though OKeeffe did strike up a close friendship with Harlem Renaissance writer Jean Toomer in 1934, when she was 46 years old (its open to question whether or not this relationship was consummated), she seems to have foresworn ordinary romance. In 1948, OKeeffe relocated permanently to New Mexico, where she remained based for the final 38 years of her life.

As her reputation grew as the grande dame of American art, OKeeffe also became known for her crankiness and combativeness (behavior that she had earlier seen demonstrated by Stieglitz). She enjoyed the perquisites of fame, jetting around with rich pals and patrons, garnering ever more awards, solo museum exhibitions and honorary degrees.

At the same time, she gained a reputation as a recluse. Seemingly health-obsessed, she read Adele Davis, drank protein supplements and insisted that sugar was "poison." She could come off as downright misanthropic; in a 1967 Vogue profile, E.C. Goosen called her "almost totally unsentimental," and claimed that she "barely tolerates sentimentality in others." As OKeeffe herself once put it, "My pleasant disposition likes the world with nobody in it."

In the second half of her life, OKeeffe tended to encourage intimate relationships with her employees, who she would later snub, treating them merely as paid assistants. Maria Chabot, a 26-year-old aspiring writer, met the 53-year-old OKeeffe in 1941, and worked for her for the following eight years, helping to build the house in Abiquiu to which OKeeffe would eventually move permanently. The two corresponded extensively, went on camping trips together and became confidantes. Though there has been speculation that Chabot and OKeeffe became lovers, Drohojowska-Philp puts that myth to rest.

In 1947, OKeeffe met yet another adulatory 20-something, the avid Doris Bry, who became the painters manager. (In fact, Bry was originally in the employ of Dorothy Norman, but OKeeffe offered her more handsome remuneration.) Eventually, OKeeffe dropped Bry for the sculptor Juan Hamilton, a strapping young man who came knocking on her door at Abiquiu in her last decades, looking for work, and went on to become her traveling companion and manager. At times, in the company of others, the pair would joke about marriage, and OKeeffe at one point changed her will in favor of Hamilton.

While OKeeffe could be harsh, this quality often worked wonders for her career. Far from being runic or oracular -- as one might suspect, given the photos of a sphinx-like woman, draped in shawl, out in the desert -- the older OKeeffe often comes off as whip-smart, managing the business of her art with cold efficiency.

She was stubborn when it came to the usual prerogatives of curators. After Stieglitz died, for instance, many of his photographs went to the Metropolitan Museum of Art. The head of the print department argued for cutting down the size of the mats on which they were mounted, telling OKeeffe, "This is the way we do our Rembrandt prints." The painter countered with "Well, Mrs. Rembrandt isnt around."