In a seeding implement, an opener assembly including a compact, arc-shaped opener with a point supported below the surface of the ground during the field-working operation to prevent hairpinning of trash and allow high-speed seeding. The compact configuration reduces variations in seed placement and minimizes side bend forces. The nose configuration of the opener limits the amount of soil that is lifted and thrown to accommodate narrow row spacings. A notched structure is removably mounted on the boot standard of the assembly and the opener is attached to the structure with a single pin. The support structure bears substantially all the loading on the opener during operation and provides convenient mounting and removal of the opener.