This sterile style is from a functionally staminate flower.
The flower head is composed of functionally staminate florets in the centre and a few pistillate florets on the periphery. The functionally staminate florets contain pollen producing stamens and an unbranched, sterile style. The pistillate florets posses no stamens, an ovary, and a two-cleft style. Upon maturity the pistillate florets produce the only fruit (achenes) in the head.