A seeder (10) comprising:- a support bar (20),- at least a first seeding unit (31) associated to the support bar (20),- an extension bar (25) of the support bar (20), rotatably associated to the support bar (20) with respect to an oscillating axis (B) and mobile between a raised position, in which it is substantially perpendicular to the support bar (20), and a lowered position in which it is substantially parallel to the support bar (20) so as to axially prolong the support bar, and- at least a second seeding unit (32) fixed solidly to the extension bar (25) and mobile therewith between the raised position and the lowered position.
