Viola (odorata or tricolor)

[ReneZ]

I can accept that the plant apparently shown on You are not allowed to view links. Register or Login to view. in the Voynich MS would not have been associated with the name 'Viola' in the early 15th century. This means that the scenario I proposed, where the 'artist' mistakenly drew the wrong viola, triggered by the appearance of the name, is not too likely.

It still seems possible that he was drawing from descriptions. 

For this case, with the upside-down flower, drawing from a dried specimen is quite a credible scenario, but that would not explain why many other plant seem to be composites.

The point remains that he was quite good at drawing realistic details.

A combination of drawing from nature and drawing from earlier illlustrations, in a single book, is not at all unusal. 

With respect to recognising the important distinguishing features of plants, the classical works of Theophrastus go into that, but it was notoriously unknown in the middle ages. It seems to have appeared in Padova right about the time of the creation of the Voynich MS, brought there by Aurispa. It was only translated to Latin in 1483.

A typical example is the distinction between alternating and opposite leaves, which was largely ignored, and can be seen to appear combined in the same plant in many old herbals. I don't know if anyone ever did a detailed check of this in the Voynich MS.