To a botanist, an aphyllous plant is one that exists without natural foliage, such as a succulent or cactus. “Aphyllous” comes from the Greek root “phyllon,” meaning “leaf,” and the prefix “a-,” meaning “without.” The Greek word turned into the Latin “folium,” which is also the root of “foliage.” If you’re not a botanist, you might want to use this adjective to describe trees that have lost their leaves in the fall or for neglected plants that have withered.