I always work from photos.
I use real dirt, glued down tan felt, real rocks for talus and debris. I glue the tan felt down using acrylic contact cement (Elmer's) and airbrush green or brown in patches on it. Then I lay down real dirt (which has been baked for at least an hour at 400 degrees to kill any fauna and flora) which has been sifted into three or four grades or coarsness, starting with the finest "dust" and teasing up felt fibers through it. I add coarseness as I'm teasing it. I sock it down with an liberal spray of wet water, then I run diluted Matte medium onto the felt/dirt combination, being careful to get everything "fixed" but not too soaking wet.
After that's dry, I tease up more fibers, separate the clumps and trim it to length.
Then, I sometimes will sprinkle a bit of ground foam onto it after wetting it with hairspray to represent seed pods.
Depending on how I pull up the felt fibers through the dirt (tease it up) I can make very good representations of field grass, grass around streams and rivers, and bunch grass on the side of a western hill.
Bushes are easy and consist mainly of pieces of green or dark brown Polyfiber which I've rolled up into little balls (for Junipers) or strung out in rough lines (weeds up against a fence or in a gully and previously dusted with a good coating of ground foam after I've sprayed it liberally with hair spray.
Green 3M pads also work pretty well for thicker ground cover such as "scrub oak" trees which are plentiful here in Utah. Spray 'em with hairspray and dust on the ground foam.
Some places are just bare dirt with a fairly even coating of grass, and this is where my Noch GrasMaster comes to work. I use a mixture of Noch and Woodland Scenic's "static grass" both in colors and lengths. Nothing worse than having a static grass section look like a green butch haircut! I especially like the Noch fibers that have three different length of fibers in them. After I apply my little section of static grass, I moosh the "grass" around so it isn't at all even or uniform....then let it dry. I vacuum up the leftovers with a cloth over the crevice tool which allows me to salvage some of the static grass.
If you want to make bunch grass, get a Teflon lined aluminum cookie sheet and spot it with Elmer's Glue All, then attach your grounding wire to it, and use your static applicator to shoot fibers into the wet drops. I shoot from the sides as well as the top to get the fibers to be spread out in all directions on each drop of glue. When the glue dries, it'll be more flat, and those fibers that were nearly horizontal will be sticking up a lot more.
Then, you scrape them off the Teflon no-stick surface with a spatula after they dry. Goes quick and they're easy as pie (or cookies) to make! I glue them to my terrain with a spot of matte medium. The Noch multi-length fibers work great for this.
In some places I also use some old horse-hair that I bought all cleaned and packaged (I bought a lot of it) trimmed and positioned to look like long stems.
Here's a photo of Wilhemina Pass that I've posted before using real dirt (dug from the actual spot), teased up felt with real dirt on it, some horsehair bushes, Polyfiber bushes and torn up 3M pads for the scrub oak on the north sides of the talus slopes. The only ground foam is on the trees, Polyfiber and 3M pads. I didn't use my Static Master in this scene (I didn't have it yet) but if I'd had it, I would have put more grass near the water's edge:
Yes, and I used photos and videos I took of this actual spot. They were absolutely invaluable as was digging three buckets of different colored real dirt from the area too.
