Glory
You keep this green earth as it should be - green. You make beautiful lawns, gardens, and parks possible. That's pretty glorious.
However, you won't be winning any awards or medals. You won't even get noticed for your day-to-day work. You'll grow or bring in plant material that the retail nurseries or landscapers want and deliver it as instructed. And that's about it.
You might gain some fame in horticultural circles for breeding a new kind of plant, or marketing it. This is kinda risky, though. For one thing, you never know if it'll take or not. And for another, if the new varieties make it big, the retail nurseries or landscapers get the credit. But deep down, you'll know who's really responsible for that great bit of gardening.