Six onion-roof towers supporting heavens

[Jorge_Stolfi]

It is simply a scientific book, scientific for its time of course. It is true that there are not many religious symbols, but there are enough to consider it a work of Christian tradition. We have ... the dove of the Holy Spirit (f86v3); a stem that coils like a bishop's staff (f56r); [the herb with] a root shaped like a beast, leaves shaped like spears, and flowers resembling the nails with which Christ was nailed to the cross (f90v1).

Those are not evidence of "Christian tradition".  These interpretations are not the answer one would get from asking any "fresh" observer "what is this?".  They are answers to "if this was a disguised Christian symbol, what would it be?"

And there are problems in these interpretations.  

Why are there two "doves of the Holy Spirit" on f86v3?  And why is one of them sitting in a nest?

The petals of the flowers of f90v1 may look like nails at first sight, but they are in fact hollow, like square trumpets.  

 the female figure holding a cross (f79v)

That indeed is hard to see as anything but a cross. 

However, there is a possible problem with that one too.  I cannot discuss it here, but you may guess it by trying to understand what is going on with the third nymph on that page's margin:
   
What do you see there?

All the best, --stolfi