Georgia O'keeffe
Modern art refers to artistic works produced during the period extending roughly from the 1860s to the 1970s, and denotes the style and philosophy of the art produced during that era.[1] The term is usually associated with art in which the traditions of the past have been thrown aside in a spirit of experimentation.[2] Modern artists experimented with new ways of seeing and with fresh ideas about the nature of materials and functions of art. 

In art history, this term refers to the philosophies of art made in Europe and the United States during a period roughly from the 1860s through the 1970s when certain artists began to take radical steps away from traditional art in order to be deliberately different, critical, and often dissenting from the dominant official taste. Modern art or modernism is characterized by changing attitudes about art, an interest in contemporary events as subjects, personal artistic expression, and freedom from realism. Modernism can be seen as artists' attempts to come to terms with urban, industrial, and secular society that emerged during the 19th century in Western society.(http://www.artsconnected.org/artsnetmn/environ/okeeffe.html)

"American Modernist Painting began to coalesce with the Armory Show of 1913, and lasted through the Great Depression. American modernists were diverse, including Precisionists, scene painters, and abstractionists, and looked both to Europe and to homegrown styles for their influence."(http://www.theartstory.org/artist-okeeffe-georgia.htm)
characcteristics:
Creating new techniques
emphasis on originality 
"Georgia O'Keeffe spent eighty years constructing her life as an artist who helped pave the way for the development of modernism in America."(http://www.theartstory.org/artist-okeeffe-georgia.htm)

Other Artists

Picture
Arthur Dove. Me and The Moon. 1937. Phillips Collection Wshington D.C.
Other  American Modernism artists:
John Marin
Arthur Dove
Aaron Douglas
Alfred Maurer
Max Weber




Picture
Cow's Skull: Red, White, and Blue.1931
  1. A single animal bone isolated from its enviroment.
  2. "Cow's Skull: Red, White, and Blue" is masterful, both as an eloquent abstraction of form and line and as a richly symbolic image that raises issues of nationalism and religion."(http://www.metmuseum.org/works_of_art/collection_database/)
  3. Simple composition

Picture
Two Calla Lillies On Pink.1928.The Georgia O'Keeffe Foundation / Artists Rights Society (ARS), New York
  1. Abstracted flowers
  2. Sweeping brushstrokes
  3. A pink backdrop with two bright yellow pistols
  4. "What is my experience with a flower if not with color?"(http://www.philamuseum.org/collections/)