Calyx protects the flower in bud stage. Outermost whorl of flower is calyx. Unit of calyx is sepal. Normally green in colour.
a. Aposepalous (polysepalous or chorisepalous): The flower with distinct sepals. Example: Brassica, Annona.
b. Synsepalous: The flower with united or fused sepals. Example: Hibiscus, Brugmansia.
What is the green part of brinjal fruit? Have you seen similar to this in any other fruits?
a. Caducous or fugacious calyx: Calyx that withers or falls during the early development stage of flower. Example: Papaver.
b. Deciduous: Calyx that falls after the opening of flower (anthesis) Example: Nelumbo.
c. Persistant: Calyx that persists and continues to be along with the fruit and forms a cup at the base of the fruit. Example: Brinjal.
d. Accrescent: Calyx that is persistent, grows along with the fruit and encloses the fruit either completely or partially. Example: Physalis, Palmyra.
Have you noticed the shoe flower’s calyx? It is bell shaped called Campanulate. The fruiting calyx is urn shaped in Withania and it is called urceolate. In Datura calyx is tube like and it is known as tubular. Two lipped calyx is present in Ocimum. Sometimes calyx is coloured and called petaloid. Example: Saraca, Sterculia. Calyx is distinctly leafy,large and often yellow or orange coloured sometimes white as in Mussaenda.
It is modified into hair like structure or scaly called pappus as in Tridax of Compositae.