The Cottonwood Tree, oil on paper, 11 x 8.25.
"Plein air" is a french term meaning open air. The term was coined in the 19th century when artists first began to use the outdoors as their studio. Typically executed in one session, plein air paintings are often very small. But what they lack in size, they make up for in expressiveness. They are often the landscape painter's most spontaneous and fluid expression.