The present invention relates to a spreader (1) for spreading granular or micro-granular material on the ground under gravity comprising an elongated hollow member (10) extending along an essentially vertical axis X and defining an inner cavity through which said material to be spread on the ground can flow, said hollow member (10) being adapted to be associated with a delivery conduit (50) of a container for storing said granular or micro-granular material. In particular, at least an end portion (10A) of said hollow member (10) has a substantially circular or elliptical cross section and it is provided with a plurality of protrusions (14) projecting towards the inner cavity and being adapted to even the flow of the material before exiting said inner cavity.