Georgia O'Keeffe’s first major abstract series was Series I.
She developed the series in 1915 while teaching at West Texas State Normal College in Canyon, Texas. The works used charcoal and reduced forms to explore line, rhythm, and shape rather than depicting recognizable objects. They were among the earliest wholly abstract works produced by an American artist.
O'Keeffe sent the drawings to a friend, Anita Pollitzer, who showed them to Alfred Stieglitz in New York. Stieglitz exhibited them at his 291 gallery in 1916. That presentation brought O'Keeffe wider attention and began their long professional relationship.
The series is sometimes described broadly as her early abstractions, but Series I is the specific title associated with the 1915 group. Her later paintings continued to move between abstraction and recognizable subjects, making strict labels difficult for some individual works.