Sexual reproduction in Flowering Plants
Calyx is converted into hairy pappus in
The pappus is the modified calyx, the part of individual floret that surrounds the base of the corolla tube in flower heads of the plant family Asteraceae. The Asteraceae pappus may be composed of feathery bristles, scales. In Helianthus, the calyx is converted into hairy pappus. So, the correct answer is 'Helianthus'.