Arbor vitae, Latin for "tree of life", is used to describe the branching pattern of white matter seen in sagittal sections of the cerebellum. This is not because the branchings suggest a tree or represent some kind of life-sustaining function in the cerebellum, but rather because of its resemblance to the foliage of the arborvitae, a group of ornamental plants native to East Asia and North America.

The term was coined in the late 17th or early 18th century by Jacob Winslow, the great Danish anatomist. Winslow did much of his work in Paris and presumably encountered in it Parisian gardens. Most likely he saw Thuja occidentalis, or Eastern Arborvitae (often misidentified as cedar), which was the first North American plant introduced into Europe.

The tree was brought back from the new world in 1534 by French explorers who had learned from indigenous people along the St. Lawrence River that a boiled concoction made from its greenery cured scurvy. It was thus named “l’arbor de vie” by the King Francis I and planted in medicinal plant gardens.

Winslow also named the sympathetic chain and was the first to call the ring of pigment surrounding the pupil the "iris".

Thuja occidentalis www.preservedgardens.com