A "jungle" tank usually means one with lots of stem plants. If those are allowed to grow without any pruning at all, you end up with a very ugly mess. The tops bend over and grow along the water surface, the bottoms get shaded so much the leaves look bad, or die off completely. Soon the water surface is so crowded not enough light gets thru to keep any of the lower plants growing, and the swimming space for the fish gets smaller and smaller. The best looking "jungle" plants have been pruned regularly to keep them under control, so it is not a plant and forget tank at all.