One definition is: "The small tubular flowers in the central part of a floral head. Example: Daisy." but there are some flowers which do not have petals like the daisy, and have only the center disc--in this case, many central discs.
I am a Grandma blogger, posting some regular stuff on some regular blogs--photos and memes. Most recently I have primarily participated in a weekly header challenge, but hopefully I will get back to more regular blogging again.