Green is not just yellow and blue; the varieties are endless thanks to the creative folks at all the paint manufacturers.  I've attached a color chart of the greens I use. My favorites are Daniel Smith Olive, Undersea, Perylene Green, and Prussian Green. Also, Windsor Newton Olive (way different from Daniel Smith!). Cascade Green is nice too, but a bit too neutral for me. The others I use as blues - Perylene, Prussian, or as yellows - olive and undersea. The nice thing is that you COULD mix these colors yourself, but now you don't have to. To ignore green is too ignore so much of nature. It is, after all, green!