$\Rightarrow$ Sunflower is not a flower but type of an inflorescence in which receptacle is flat. It possesses many sessile and small flower buds. The smallest bud is in the centre and the oldest is located towards periphery. The group of flower bud is surrounded by a bract and it is called involucre.
Two types of flower buds are seen in sunflower:
$(i)$  Ray Florets : It is arranged on the edge of receptacle that possesses special yellow colour and band like petals. These flower buds are arranged in female sessile and always Zygomorphic, one or more whorls.
$(ii)$  Disc florets : They are located in centre, bisexual and actinomorphic.