[split] Voynich-like plants in Firenze Riccardiana Ricc. 2174

[Bernd]

Mustard flowers can vary greatly in shape, depending on cultivar and age of the flower. Here's a particularly well-matching example of Brassica nigra with shorter sepals.

   

As you noted, the VM flower is a composite that has a 'standard' Alpha-style bulbous calyx (made of sepals) and from it emerges a full cruciform flower, again with sepals and petals. Such double calyces appear several times in the VM.

Also my impression is that in this particular flower, the 4 petals were meant to depict hollow tubes, open at the end. Possibly another misunderstanding of a shaded source image similar to the one from Ricc. 2174 (which curiously lacks sepals).

They remind me of lamiaceae which often have spots on the inside to attract pollinators. Actually the VM 'petals' look more like the calyx of a lamiaceae flower like salvia. In any case, it appears to be a mix of different plants for whatever reason.