Feather-like formation of hot, rising gas in the atmosphere of a star or planet caused by convection.

The conspicuous feather or feathers of a bird (Morris 1992)

large feathers, usually worn on a crown or headdress

Plumule The plumule is a cluster of embryonic leaves at the tip of the embryonic shoot in the seed. This structure will become the first leaves to begin photosynthesis and turn green when the shoot tip reaches the sun. DIAGRAM: Cotyledons Acorn PHOTO

The way polluted water extends downstream from the pollution source (analogous to smoke from a smokestack as it drifts downwind in the atmosphere).