I came across these vast flower fields on a mountain biome, stretches for hundreds of blocks. I don't think it's a flower forest biome because it only spawns large bursts of one variation of flower at a time. There are also beehives on about 80% of the trees in the area. If you notice any texture variation on the flowers that is because I am using a texture pack. But to make sure that this wasn't due to any active resource packs I loaded, I made another world with the same seed and it was the same. I made a number of other worlds and I still came across these huge flower fields. This also seems to happen only on the new very tall mountains introduces in the new terrain generation.