How often do we see plants on the Ground? So far (in the anime, manga readers please do not spoil, I haven't gotten far yet) the only ones I can think of are the trees from Zanka's flashback and the meager Garden from Delmon's Amo-induced hallucination. There might be tiny patches of grass here and there, but that's still a big lack of plants.
And trees do a lot of heavy lifting for atmosphere conditions and air quality, so the lack is telling of just how bad life on the Ground can be.
Not to mention the lack of flowers means that flowering plants that humans eat like apples, pears, tomatoes, broccoli, squashes, cucumbers, melons, cherries, plums, lemons, peaches, eggplants, and so much more.
Not only have the beasts of burden mutated under the pollution caused by the Sphere, but a lot of plants and animals would have had to adapt to the conditions or wound up dying out completely.
What I'm saying is that the Vianders and other associates must do a lot of heavy lifting to make things that are not only safe for human consumption and nutritious, but also actually taste good.
I mean, just how much work do they have to do that they have sugar? Something that in real life cost thousands of lives when it was being mass produced by slave labour in plantations. They have ice cream; do they have vanilla? Do they have honey? Are bees still around? Are there enough flowers to continue making honey? Or do they have honey from the before times stored away for special uses only? I have so many food-related questions because food is how people not only survived but live!
Don't even get me started on medicines!
