Arillos

Arillos is a term used in botany to describe the fleshy, often brightly colored outer part of certain fruits, specifically within the seed. This fleshy layer is distinct from the pericarp, which is the fruit wall. Arillos are derived from the ovule, the structure within the ovary that contains the female gamete. They are not technically part of the fruit itself, but rather an accessory structure that surrounds the seed.

The presence of an aril is a significant feature in the classification and identification of some plant species. These structures are believed to play a role in seed dispersal, as their attractive appearance and often sweet taste can entice animals to consume them. The animals then excrete the seeds, often at a distance from the parent plant, aiding in propagation. Examples of fruits with arillos include the nutmeg (where the aril is the mace), lychee, and rambutan. The texture and flavor of arillos vary greatly among species, ranging from dry and papery to juicy and succulent. Some arillos are edible and widely consumed by humans, while others may be unpalatable or even toxic. The study of arillos is an area of interest in plant anatomy, ecology, and evolutionary biology.