An invention providing a scanning electron microscope composed of a monochromator capable of high resolution, monochromatizing the energy and reducing chromatic aberrations without significantly lowering the electrical current strength of the primary electron beam. First through third semiconductor films are formed on a first insulating film. The bore of the holder comprises an inner surface comprising a hardness greater than 58 HRc. The invention relates to sunflower seeds, to sunflower plants, and to methods of producing a sunflower plant.