I had a sheet of 4mm MDF and got to work with a jigsaw cutting out lots of shapes for this and other stuff, plastered them with a generous amount of PVA glue and then my trusty rough sand, and using a variety of acquarium plants acquired from Pets at Home got sticking them on with a hot glue gun. I've finished some off with a few twigs to represent fallen logs and some tea leaves - dried out again or not used in the first place, which was a tip I picked up on another blog and makes passable leaf litter. Both regular brown and green Chinese tea works well for this, and I used a combination of both.
I started with large 'stands' which are handy for putting down a couple to represent a reasonable sized area, but I also went on to try out basing them on some smaller bases and even coins. I found a variety of different sizes bases worked well for covering a bigger area. As the top photo shows a single A4 box when closely packed for storage can be spread out to cover about 4 feet by 2 feet and still look like dense jungle. It also looks even better when you add add palm trees (more 'island look') or just normal model trees (more 'rainforesty look') or both - sorry I didn't have these to hand when I took these shots-and doing so also increases the table coverage you can get from this much jungle.
In the event I probably only got half or less of what I wanted to get done completed, but this was largely down to running out of storage boxes which I thought I'd ordered in generous enough quantities but obviously not! I've got plenty more plants and have done another tray of bases already so, I can whip up some more when I've got more storage boxes.