səˈrēdēəm noun
( plural sore·dia -dēə)
Etymology: New Latin, irregular from Greek sōros heap + New Latin -idium; akin to Latin tumēre to swell — more at thumb
: one of the vegetative gemmae on the surface of the thallus of a lichen consisting of a tuft of hyphae investing a few algal cells or gonidia — called also brood bud, hologonidium