What is "synsepal"

A synsepal is a floral structure formed by the partial or complete fusion of two or more sepals. Such sepals are said to be gamosepalous.

It is common among Lady's Slipper orchids ( Cypripedioideae) that the two lateral sepals are connate to form a synsepal in the outer whorl. This is located directly behind the pouch, opposite the upward-pointing dorsal sepal.

Synsepals may be bifid, i.e. divided into two equal lobes, or forked and divided in two by a deep cleft.