Locating a particular herb in the wilderness can be a daunting task even to an expert. Many of the herbs which the Siddhar practitioners have documented are known to grow on steep rocky hillsides in Southern India. Siddhar Agasthiyar says that locating herbs is an easier task from a state of heightened awareness. He says in his text that a Rishi who lived atop the Great hill of herbs trained him on this.
Hills which Agasthiyar mentions in his texts are found today in Tamil Nadu, in India. Is there also a "Great hill of herbs" which is associated with a Rishi? A possibility is the Marundhu-Vaaz-Malai (மருந்துவாழ் மலை) hill which overlooks the Indian ocean from the Southern tip of India. The name of this hill means "The Hill where Herbs reside". There is a small cave with an altar for Agasthiyar along the path to this hilltop. Reputed spiritual masters who meditated here in the recent past confirm the fact that Agasthiyar wrote some of his texts in this cave.
Agasthiyar describes the Rishi who initiated him into the art of locating herbs as the "Gandharva" Rishi. We find references to Gandharvas in the Vedic texts such as the Ramayana. Hanuman, the son of Vayu, the reputed devotee in the Ramayana, was born to a Gandharva women, an Apsara. There is a small Hanuman temple atop the great hill of herbs. Could Hanuman, who literally brought a hill load of herbs from the Himalayas be the Gandharava Rishi who taught Agasthiyar?
Here is the link to a YouTube of a young trekker who has captured the beauty of the way to the top of the hill. video https://www.youtube.com/watch?v=cXIdPnS0SpE. You can easily catch the enthusiasm and the message of the trekker even if you do not understand his narration in Tamil.