Jungle Potion

This quest has a Quick Guide found here.

Getting started
Firstly, head to the small village of Tai Bwo Wannai, found south of Brimhaven on Karamja Island. Talk to Trufitus, a native found in a small house a short distance north of the main village area. Ask him where everyone is, and he says that they've left the village.

Ask him about how you can help, and he tells you that he needs several herbs to mix a potion so that he can commune with the gods. Tell him that you'll give it a try.

Snake weed
The first herb that Trufitus needs is called Snake Weed, and it apparently grows near water. Head south of the village, past several level 44 Jungle Spiders and level 32 Tribesmen, and then west towards the water. Near the river should be a Marshy Jungle Vine, so search it to get an unidentified herb which when identified should be Snake Weed. Bring this back to Trufitus and he should give you another clue.

Ardrigal
Head north of Trufitus' hut until you reach a cliff, and then head east to a peninsula with several Palm Trees on it, and level 46 Harpie Bug Swarms. Search a palm tree to find another unidentified herb, which will be Ardrigal when identified. Bring this herb back to Trufitus.

Sito foil
The next herb required for the potion just happens to grow well in areas that have recently been burned by fire, like a campfire. Go south of the village, and towards the west side should be an area of Scorched Earth. Search it to find the herb, identify it to see that it's Sito Foil and bring it back to Trufitus.

Volencia Moss
This type of herb is commonly found clinging onto rocks that are constantly disturbed, much like a mining site. Head southeast of the hut until you reach a group of rocks and search an empty one to find the herb. Again, identify it to see that it's Volencia Moss and give it to Trufitus.

Rogue's purse
The last herb that is needed to make the potion is known as Rogue's Purse, and it can be found in a cave to the north of the village. Just head back to the cliff to the north, follow it to the east and then follow the coastline west until you reach a pile of rocks. Search them and then enter the cave. Once inside, head south past the level 53 Jogres until the end of the passage, and then search the Fungus Covered Cavern wall to obtain another herb. When identified it should be Rogues Purse, so bring it back to Trufitus.

After taking the last herb back to Trufitus, he will give you some Herblore experience and you'll be finished with the quest.

Rewards

 * 1 Quest point
 * 775 Herblore experience