So leave the magic boxes out of the mass proposal tool?

Unless they can be filled in, Yes.

If someone were to select Leaves and other but not be able to add text into the magic box. the data would appear incomplete.

They will be able to fill them in.

I'm actually making it so that you enter a latin name (genus/species or just genus) and then you fill out the data proposal exactly like you would for a single plant. The only real difference is that it affects all plants that match your latin name you give.