W

wall rock— The rock mass making up the wall of a fault or the rock forming the walls of a vein or mineral deposit.

whorl— A ring of similar organs radiating from a node, as a whorl of leaves.

wind shear— Abrupt change in wind velocity (direction and speed) with height or horizontal distance.

wing— A thin, usually transparent or papery extension bordering an organ, as a winged seed; also, a lateral petal of a pealike flower, e.g., Family Fabaceae.

winnowing— A step in seed processing in which wind and/or gravity are used to separate seeds from unwanted plant material, such as chaff.