Conservative estimates consider that there are 250, 000 plant species on earth today. Of these, only approximately 2% have been tested for properties that may have medicinal value. This is a daunting task when you think about the far reaches of the globe where many of these plants grow, let alone the lab work that is required for this kind of work.
It is obvious, though, that many plants in their natural state have been of great benefit medicinally for decades, even centuries. Some of the most commonly used by every-day people are probably chamomile, ginseng, Echinacea, aloe vera, and garlic.
Thanks to forward-thinking botanist scholars, there are something like two thousand herbarium collections of almost all the known species of plants in botanical gardens and museums around the world. In the Harvard University collection alone, there have been promising notes produced on 5000 species, most of which were not previously recognized as having medicinal ingredients.
In North America, there are at least 175 native plants that are being sold every year as non-prescription medicines for the more than 60 million American consumers that use herbal remedies.
Recently, in Australia, it has been discovered that the Australian Morton Bay chestnut contains chemicals that are being scientifically analyzed with the hope that they contain ingredients to help in the fight against AIDS. How many undiscovered plants might there be that contain healing substances?
Sadly, many of Earth's natural plant habitats are being lost daily when rain forests are destroyed and new construction scrapes the earth clean. Botanists and scientists are trying to find and study as many potential medicinal plants as quickly as possible. It is a race to help mankind.
There are groups around the world that embrace this cause and if it is something you would like to learn more about, there is a good article here: http://healthmad.com/alternative/green-medicine-a-grass-roots-approach-to-illness/