perianth

noun

1. The sterile parts of a flower; collectively, the sepals and petals (or tepals).
2. The sterile, tubelike tissue that surrounds the female reproductive structure in a leafy liverwort.

   “Archegonia are surrounded early in their development by the juvenile perianth, through the slender beak of which the elongated neck of the fertilized archegonium protrudes.”