Claude Monet's "Grainstack" series, also known as the "Haystacks" series, is a collection of paintings created by the renowned French Impressionist artist between 1890 and 1891. The series consists of around 25 paintings, all depicting stacks of wheat or hay in various landscapes.

In the "Grainstack" series, Monet focused on capturing the effects of changing light and atmospheric conditions on the subject matter. He observed the stacks at different times of the day, in different seasons, and under various weather conditions. This allowed him to explore the nuances of light and its transformative impact on the appearance of the grainstacks and the surrounding landscape.