Its name is derived from the word "hesperidium", for fruit produced by citrus trees. The kumquat-sized fruit is a red, edible hesperidium resembling a small "Citrus" fruit. The fruit is an edible red hesperidium similar to a small "Citrus" fruit. Centax-1, Centax-2, Centax-3, and Hesperidium. A hesperidium (plural hesperidia) is a modified berry with a tough, leathery rind. "Clymenia" fruits are a small hesperidium, very similar to a citrus fruit. A fruit with a thick peel, such as a citrus fruit, is called a hesperidium.