If you think that the apple tree varieties currently cultivated are over 10,000 - almost all deriving from Malus communis, a spontaneous plant growing in the forests and belonging to the Rosaceae family - you can understand that the issue is complex and a detailed description is unlikely.
Monferrato apples include four endangered varieties, relaunched today thanks to the research activity carried out by an amateur nursery man, who has prepared the necessary material for their diffusion and cultivation in some agricultural holdings using organic methods.