👉 In the context of botany, an oestrum (also known as a "stamen") is a structure found in flowers that develops from the stigma. The stigma is a protective covering on the floral part of a flower, while the oestrous structures are those that develop from the stamens. This term comes from the Greek word "ostero-" which means "within" or "under," and refers to the process by which an oestrous structure forms inside the stigma.