What is a hesperidium?

A hesperidium is best defined as a modified berry that features a leathery exocarp, which is the outer layer of the fruit. This type of fruit is characteristic of certain citrus plants, such as oranges, lemons, and limes. The leathery skin contains oil glands and contributes to the fruit's aromatic qualities. The inner part of the fruit is filled with juicy segments, which contain the seeds and are surrounded by a fleshy mesocarp. The unique structure of a hesperidium allows for the accumulation of juice and flavor compounds, making it distinct from other fruit types.

The identification of a hesperidium reflects the specific adaptations in citrus plants that help in seed dispersal and protection of the seeds within a juicier, nutrient-rich environment, thereby ensuring the continuation of the species.