Marandahir
Crown-Forester (he/him)
I think an issue with a plant race, fundamentally, is that while certainly it could offer unique possibilities in regards to the finer details of roleplaying (and also figuring out how and what they eat given that most plants are continuously rooted in the soil for a reason), there really isn't anything in terms of how the race would be in comparison to humans in the more general sense isn't so clear.
You could easily just take the Elf stat block as given, maybe add a single line about how plant people differ from mammalian ones and then just alter their fluff to make them into a race of plant people who all look more or less female but are effectively both genders at once just like Guilds Wars did.
Orcs with just a small twist of fluff and a similar line could be transformed into a race of asexual fungus creatures like in WarHammer. Half-Orcs could just be humans whose mothers got infected by the fungus spores causing the baby inside them to be mutated.
I mean, you could rationalize them being any size, having any sort of physique (except as I noted in these examples, it probably wouldn't make sense for traditional human sexes to be assigned to them-- though WotC would probably do so anyway), having any given set of skills, have either no abilities or powerful druid abilities being equally viable...
There just isn't anything you could really say about how a vegetation-based race should really be in terms of visuals, characteristics, society, etc. that everyone can really universally agree on as being generally the right direction. And whatever set of these things you gave them, chances are there is already another non-plant race they would be so similar to that they would seem redundant.
Most Plants don't eat from the soil any more than we eat from the sun. They're getting particular vitamins and nutrients from the soil, but their rooted nature is less essential than their ability to photosynthesize – that's where they get their energy from. Yes, I'm oversimplifying; we don't just eat grains to get sugars, we eat foods rich in proteins and whatnot. But there are examples of plants that find those other nutrients in various other ways: "carnivorous" plants digest insects for the sake of synthesizing nitrogen in N-poor swampland soils; most trees trade carbon to fungi and bacteria in exchange for Magnesium and Phosporous in Mg-poor and P-poor soils respectively. These could be emulated via economic systems if plants became mobile.
There ARE examples of mobile plants. In fact, many functions of plant life are about breaking through the relative rootedness of plants to access new areas with less competition. Plants grow for that very reason, and they distribute their pollen and seeds via wind or vector species for the same reasons (to "steal" their mobility).
Fungi do some similar things, despite their vast differences. Imagine a Fungal race that looks a bit like Paras and Parasect from Pokémon – the fungus is in charge, but the insect gives the fungus mobility. This is a similar idea that's been posed with the Vegepygmy, despite my big issues with that monster for reasons of their diet restrictions.