Thanks for such a quick reply and, sorry, I should have provided some more info. Here goes:
It's on a new install, new seed, new everything. I basically just installed 17.2 with a bunch of modlets, including yours, through the mod launcher. The vanilla plants I see are in the wild as I literally just started my world. I'm having no NRE or crashes or any such problems, so this is really not a huge deal, except it would have been nice to see your beautiful flower models.
I'm completely new to installing modlets, but everything else seems to work just fine. I'm surprised at how easy it was to get all these mods to work together! Still, I wonder if maybe the plant models are getting overwritten by some other mod? Could I alter the load order somehow?