What is syngenesious stamen?

The union of stamens that takes place among themselves is called cohesion. On the basis of cohesion, androecium is divided into following types i.e., Adelphous, diadelphous, and polyadelphous. The fusion of stamens with each other is called cohesion of stamens. Syngenesious stamens are those stamens whose anthers are united into a tube whereas, its filaments are free.

What is epicalyx? Give an example.

A ring of small bracts at the base of certain flowers, resembling an extra outer calyx is called epicalyx. They are a series of bracts subtending and resembling a calyx, as carnation in Hibiscus . It is exterior to the calyx. Some times, it is a resultant of union of the sepal appendages. An epicalyx forms an additional whorl around the calyx of a single flower. It is also regarded as an extra whorl of floral appendages.