Gum trees are a very common type of indoor plant. There's only one problem: if you care good for them, they become huge (and only then; mine was about 30 cm high for about six years, making about one new leaf per year. Then I transplanted it into a new pot and placed it at a sunnier spot and watered it regularly. Now, three years later, it is about 150 cm (5 feet) high, making several new leaves per week and blocking almost all light from the window.
Therefore I decided something had to be done – make a layer! Knowing that gum trees are not easy to reproduce by layering, I took special precautions. To improve the probability of root growing, I dipped the branch which I cut of from the old plant into coal. I grinded coal granules with a mortar; only fine powder has a positive influence on rooting. Then I stuck the small branch into a pot with normal soil and watered it.
To increase the chances of success, I also used a different approach. A single leaf with part of the stem was put into a glass of water. Here, also, the stem was dipped in coal powder.
Because roots normally grow in the dark, and the plant somehow senses whether it's dark around its "foot", black paper was put around the glass. Thus the plant is tricked into making roots more easily.
Good news! it seems that the branch I cut off started to make roots; of course I can't see them because they're in the soil, but the plant starts using more water than it did during the weeks before, so I guess that's because it really starts growing.
By the way, did you know that the gum tree, Ficus elastica belongs to the same group of plants as the "Benjamin" Ficus benjamina? And did you know the Benjamin is really female, because the latin word ficus is female, the genetive is ficūs (for those with non-unicode browsers, a long u).
The layer made from part of the stem of the gum tree really starts growing! See the first new leaf it has made! The leaf is growing day by day, and has already unfolded fully now.