Dana Scott proposed Philodendron as plant id for fol. 6r of the Voynich Manuscript in 2001. Steve D chose specific one - Philodendron bipinnatifidum. This plant id is probably the best argument for New World species in the VMs I've seen. If true, it would place the manuscript in 16th century and later.
My own proposal for the same plant is Groundsel (Senecio vulgaris). It was used since Dioscorides to expel kidney stones, which could be the meaning of the thing 'coming out' of the buds. It is a plant included in the Pseudo Apuleus herbal manuscripts (the example is from Bodleian Library here ).
I also like Edith Sherwood's idea - Bear Breeches (Acanthus mollis).