A phytotron, according to Carter Williams, is much more than a greenhouse; it is a laboratory where scientists can grow and study plants. The building allows a fine degree of control over the growing environment. Willams designed another phytotron around the same time at North Carolina State University at a time when few existed in the world and only one other in the United States. The Duke University Phytotron is a steel-framed structure with glass curtain walls and repeating pyramidal roof forms.