For this analysis, I only considered plants in the international version of PVZ2 (although even if you group all games together, it doesn’t really improve all that much). I’ll send two images that have a simplified and approximate version of the phylogeny of plants as we currently understand it. For context, I study Santalales, which are a group of parasitic plants within ANGIOSPERMS (for reference, it’s where Missile Toe is).

Well, for starters, not everyone is familiar with the phylogeny, so let me explain it: in order to better understand the diversity of life, scientists decided to organize all the different species within different groups, each of which has a smaller group within and so on, until you arrive on the species themselves. They also organized it according to the evolution of such groups (which I’ll call clades from now on), so, for example, on Image 1, you can see the bryophyte groups (hornworts, mosses and liverworts) diverged before lycophytes. This doesn’t mean bryophytes are more primitive, just that they decided to be different before the lycophytes did.

Image 1 has all big plant clades in a rather simplified way (yes, the green algae are considered plants). Consider each of these big clades ramifies into various smaller ones called ORDERS (tip: plant orders always finish with “ALES”, meanwhile the clades within such orders, the families, always finish with “ACEAE”). Image 2 gives a better look into the most diverse plant clade, the Angiosperms. What I’ve done is to organize all plants in PVZ2 accordingly to the clade they belong into irl, with the exception of stuff like tumbleweed (could be many different plants) and the funghi (which are also poorly diverse but OK).

Image 1: https://imgur.com/a/G9HZeZI
Image 2: https://imgur.com/a/VBtmoyD

Well, all this is to say: PVZ2 lacks in diversity of plant groups. As you can see inside the ANGIOSPERMS, there are some orders (like Asterales) which include a bunch of plants, whereas others, mostly the ones next to monocots, have 0. Since I study Santalales, I also can’t avoid pointing out it has literally only 1 plant, even though there are a bunch of interesting Santalales (examples: giant flower Rafflesia, Balanophoraceae, all of which are parasites, just like mistletoes). But then you zoom out into image 1 and you realize there are literally only 3 plants that are NOT within ANGIOSPERMS, even though each of those other clades have many orders inside them. So, there could be many ideas derived from each of those clades, but the main benefits come from different game mechanics (example: parasitic plants requiring you to kill another plant before placing them (could be a good way of balancing Missile Toe)) and overall plant designs.