I too didn't feel like wating for the new jungle set to come out and I wanted some swamp themed LOS blockers. So I pulled out some old aquarium plants I had been holding onto and went to work. I actually did a little mix and matching of different plant parts to get some origonal looking ones. They were pretty simple, here is the basic formula.
The plants already had a stem so I just drilled a hole of the same diameter as the stem, into the center of the tile. Then put the stem in the hole and glued it in place using crazy glue. I then covered the tile around the plant with some model railroad grass I had. I tossed the packaging along time ago so I don't know what the offical name of it is but you will see that I use it quite a bit. It's just a personnel preference but I like it better then the standard flock used by most as it is thicker and fuller. I always felt the grass flock used on most figure bases makes it look like everyone is fighting on a golf course green.
On this one I actually used a small nail (with the tip clipped off) to stablize the plant as it was so tall. I just slid it up through the hole I had drilled and into the center of the plant. Now it does not tip over.
These two were made on a double tile as I thought they looked good together. I painted the base green but didn't like the color so I extended the grass out to the very edges to cover it up. I also painted the bud at the top of the one plant so give it some more color.
I have two of these bushes but only took close ups of the one as they are exactly the same. I thought these would work great as movement blockers as well as LOS bloskers and they do. I used a 3 tile base and drilled the hole in the very center of it where the 3 tiles come together. Since it was such a full bush I did not add any grass to the base on these.