Grimy ardrigal is a herb that is obtained by searching for the short palm trees, located on the north east area of Tai Bwo Wannai of Karamja, near the coast of the Harpie Bug Swarms. It can be cleaned to obtain clean ardrigal. It is the second herb Trufitus asks you to bring him during the Jungle Potion quest and is also used in the Legends Quest. As of now, this herb is only used to make the Bravery potion in Legends' Quest. Although, if you "use" it on Trufitus after the quest, he'll give you a few coins for it.
It cannot be identified until you have finished the Jungle Potion quest. Cleaning this herb gives 2.5 Herblore experience points.