Modified hairy calyx is

A. Pappus is the modified hairy calyx.

B. Perianth is the whorl name for tepals. It is used to denote a condition when the calyx and corolla are absent and instead of sepals of petals, tepals are present.

C. Epicalyx refers to the involucre that is present exterior to the calyx.

D. Accrescent is the condition in which the calyx continue to grow after flowering.

Hence, the correct answer is 'Pappus'