I have read some on feng shui and understand that proper placement of furniture and other things should improve the health of people, but not having any houseplants I have never thought about using it for their placement. My book is in the bedroom and hubby is still asleep, when I get the chance I will see if there is any referrence to house plant placement in it.
I got busy yesterday with family and have just had the chance to check my book. Plants can be used to improve the flow of Chi (life energy) instead of using mirrors, windchimes, etc. And as an enhancer of Chi, they would also be benefiting from the Chi that is around them, making them healthier too. Aloe plants are recommended for the Health area of a house or room. Large houseplants or small trees are good for the Wealth and Prosperity area. I have read that some Feng Shui Practioners also consider the meaning of a plant when deciding which area it should or should not be placed in.