CALYX

The outermost whorl of the flower which is made up of sepals is known as Calyx. A leaf like division usually green in colour and individual member of the calax is known as sepal.
Sepaloid : like a sepal ; green in colour
Petaloid : like a petal ; coloured
According to the depth of the divisions,calyx is of four types:
1. Toothed : Divisions very small.
2. fid : Divisions reach up to the depth.
3. Partate : Divisions reaching up to half.
4. Connate : Fused at the base.

The calax may be made up of free and united sepals.The free sepals are known as Polysepalous, whereas the united sepals are known as gamosepalous. Depending upon the shape, gamosepalous calyx is of following types:
Campanulate(Shaped like a bell e.g:-petunia)
Cupulate(Shaped like a Club e.g:-Gossypium)
Globose(Swollen like a globe e.g:-Physalis)
Tubular(tube shaped e.g:-Verbena)
Pappus(Modified into hairy structures e.g:-Sonchus)
Infundibuliform(shaped like a funnel e.g:-Atropa)
Bilabiate(Two-lipped e.g:-Salvia)
Spurred(With a long beak or spur e.g:-larkspur)
Spinous(Sepals are spinus e.g:-Trapa)
Caducous(Fall down immediately after opening of flowers. e.g:-Argemone, Papaver)
Persistent(Remaining attached till maturation. e.g:-Solanum nigrum)
Deciduous(The sepals fall of along with the petals at maturity after fertilization. e.g:-Brassica campestris)