The cross and the presence or lack of Christian influences

[VViews]

Are there many examples of crosses in other herbal manuscripts of that period?

That's a strange question: crosses do not appear in the Voynich herbal sections. 

I'll add that, considering the fact that the crosses appear in Q13 (except for those on 116v), the relevant question would be "are there examples of crosses in balneological manuscripts?", and the answer is yes, and actually in exactly the same context as they appear in the Voynich (held by a figure and at the top of a structure) as can be seen in the oft-cited Balneis Puteolanis manuscripts.

Italy, ca. 1400, MS G.74 fol. 34v

Italy, 13thC, Ms. 1474, Biblioteca Angelica di Roma