It is not easy to discover whether the soil is polluted by the heavy metal. Different plants including indication plants and hyper - accumulating plants can show the effects of the pollution degree.

The plants grow particularly well at the most frequent resting spots for the umbrella. As time passes, these plants, although growing slowly, will become an indication of the user's habits.

As time passes, these plants, although growing slowly, will become an indication of the user's habits.