How can one prove by the structure of a fern that a fern never blooms?

If you look at the ferns that grow in Russia, you can see that they consist only of leaves, they, unlike flowering plants, do not have stems, pedicels and other devices on which flowers could be attached. And in summer, brown spots can be seen on the back of the leaves. These are the reproductive organs of ferns, spores. And, as you know, flowering plants do not produce spores. All this proves that ferns do not belong to flowering plants and cannot form flowers.