Thompson is a medium-sized grapefruit, oblate to spherical in shape, virtually seedless, with very smooth, light yellow skin. Its flesh is tender and juicy, sometimes showing a slight pink tint, and has a pleasant flavor similar to the Marsh variety. The tree is vigorous, large, and highly productive, and the fruits hold well on the tree while also shipping and storing effectively. This variety originated as a limb sport on a Marsh tree in Oneco, Florida, and was introduced in 1924 by the Royal Palms Nurseries. It was quickly adopted for its quality and seedlessness, before gradually being replaced by more deeply pigmented clones. Thompson remains of horticultural interest for its unique characteristics and its historical role in the development of seedless, pigmented grapefruit varieties.