What is remaining beyond the period when parts of the same kind sometimes fall off or are absorbed; permanent; as, persistent teeth or gills; a persistent calyx; -- opposed to deciduous, and caducous called?

persistent — (Biol.) Remaining beyond the period when parts of the same kind sometimes fall off or are absorbed; permanent; as, persistent teeth or gills; a persistent calyx; -- opposed to deciduous, and caducous. (Webster's 1913.)

Sources