excipule

An excipule is a botanical term referring to a cup-shaped or sac-like structure found in certain fungi, particularly within the division Ascomycota. It is the outermost layer of a fungal fruiting body, known as an ascocarp. The excipule is typically composed of vegetative fungal cells, called hyphae, and its primary function is to protect the developing reproductive structures, the asci, which contain the spores.

The morphology of the excipule can vary significantly among different fungal species. It may be smooth or textured, fleshy or tough, and can range in color. In some cases, the excipule may be fused with the substrate or detached. The cells forming the excipule are generally sterile, meaning they do not directly produce spores. However, they play a crucial role in the overall development and survival of the ascocarp.

The term excipule is most commonly associated with cup fungi, which are a type of ascocarp that has an open, cup-like shape. In these fungi, the excipule forms the outer wall of the cup, enclosing the hymenium, the fertile layer where asci are found. Understanding the structure and composition of the excipule is important in fungal taxonomy and identification, as its characteristics can be diagnostic for distinguishing between different species.