perianth noun2 •The sterile parts of a flower; collectively, the sepals and petals (or tepals). •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. — 1992 formsperianths
