Seeder having: - a leg intended to be drawn by an agricultural vehicle in a direction of forward movement, the leg extending in a median longitudinal plane (P m), - a share for loosening the ground, which is rigidly fastened to the leg, - a seed dropper having a main distribution tube opening via a lower opening, a main base to which the main distribution tube is rigidly fastened, and an adapter, which is rigidly fastened to the leg, the main base being rigidly fastened to the adapter in a position that is adjustable relative to the adapter: - in translation along a first axis of translation (X 36), and - independently of said translation, in rotation about a first axis of rotation (Y 36, Y' 36) perpendicular to the first axis of translation (X 36), the seeder also having: - a plurality of first "translation" orifices, which are aligned along said first axis of translation, - a first pivot extending along said first axis of rotation (Y 36), which is housed in one said first translation orifice, the first translation orifices being provided in the main base and the first pivot being rigidly fastened to the adapter, or the first translation orifices being provided in the adapter, the first pivot being rigidly fastened to the main base, - a plurality of first "rotation" orifices, each first rotation orifice having a circular buttonhole shape centred on a respective first translation orifice, and - a first slider, mounted so as to slide in the first rotation orifice corresponding to the first translation orifice in which the first pivot is housed, the first rotation orifices being provided in the main base, the first slider being rigidly fastened to the adapter, or the first rotation orifices being provided in the adapter, the first slider being rigidly fastened to the main base. - a leg intended to be drawn by an agricultural vehicle in a direction of forward movement, the leg extending in a median longitudinal plane (P m), - a share for loosening the ground, which is rigidly fastened to the leg, - a seed dropper having a main distribution tube opening via a lower opening, a main base to which the main distribution tube is rigidly fastened, and an adapter, which is rigidly fastened to the leg, the main base being rigidly fastened to the adapter in a position that is adjustable relative to the adapter: - in translation along a first axis of translation (X 36), and - independently of said translation, in rotation about a first axis of rotation (Y 36, Y' 36) perpendicular to the first axis of translation (X 36), - in translation along a first axis of translation (X 36), and - independently of said translation, in rotation about a first axis of rotation (Y 36, Y' 36) perpendicular to the first axis of translation (X 36), the seeder also having: - a plurality of first "translation" orifices, which are aligned along said first axis of translation, - a first pivot extending along said first axis of rotation (Y 36), which is housed in one said first translation orifice, - a plurality of first "translation" orifices, which are aligned along said first axis of translation, - a first pivot extending along said first axis of rotation (Y 36), which is housed in one said first translation orifice, the first translation orifices being provided in the main base and the first pivot being rigidly fastened to the adapter, or the first translation orifices being provided in the adapter, the first pivot being rigidly fastened to the main base, - a plurality of first "rotation" orifices, each first rotation orifice having a circular buttonhole shape centred on a respective first translation orifice, and - a first slider, mounted so as to slide in the first rotation orifice corresponding to the first translation orifice in which the first pivot is housed, - a plurality of first "rotation" orifices, each first rotation orifice having a circular buttonhole shape centred on a respective first translation orifice, and - a first slider, mounted so as to slide in the first rotation orifice corresponding to the first translation orifice in which the first pivot is housed, the first rotation orifices being provided in the main base, the first slider being rigidly fastened to the adapter, or the first rotation orifices being provided in the adapter, the first slider being rigidly fastened to the main base.