So I recently came across this game (Asterix & Obelix XXL 2: Mission Las Vegum) and was impressed by all the foliage in the first level.
The game itself is old, so it was made around the limitations of non-shader consoles (i.e PS2).
It starts at around 20 seconds:
https://www.youtube.com/watch?v=IfV-MUBPWw0&feature=player_detailpage#t=18
It's also hard to see, but I think there's also a LOD system in place (i.e the grass fades in and out of view depending on how close you are to it).
Replies
http://wiki.polycount.com/wiki/GrassTechnique
Here's some sample. You can sort of tell they're planes. http://www.cgtrader.com/3d-models/plant-tree/grass/cattail-grass-texture
With some creative placement you can hide the planes really well. http://www.cgtrader.com/3d-models/plant-tree/grass/grass-texture
It's common with alpha-blended 3D graphics.