Gout tuber

Gout tubers can be planted in a herb patch to grow Goutweed. (However, it can't be planted at the disease-free Troll Stronghold herb patch.) The goutweed can be traded to Sanfew in Taverley for other herbs. It is an item required for the medium task in the Karamja Diary. The gout tuber became a very sought item after the release of the achievement diary. It is necessary in order to make a gem-bladed machete from Safta Doc, and therefore, to complete the medium tasks.

Caution: Do not left click your gout tuber, the first option is eat! (Consuming a gout tuber will restore the player's energy by 100%, although players are strongly discouraged from eating them due to their rarity)

When found while hacking jungle the message is, "You hack away the remaining bush to reveal an unusual plant." The unusual plant only has an examine option, which sends the text "Many plants such as this usually have exotic tubers". You can use a spade on it, getting the message "You dig up this plant and find a tuber" and a gout tuber.

Trivia
It is possible if more than one person starts digging up a gout tuber random event at the same time then both players will dig up a gout tuber.

Ways to obtain

 * Found randomly during the Tai Bwo Wannai Cleanup minigame. (Aside its very low frequency, it is a normal event while hacking any jungle, not just Dense jungle; as such, it is possible to get it any of the four required strikes to hack a jungle completely, not just the last one)
 * Buy from other players (Grand Exchange included)
 * Trade 200 trading sticks at Gabooty's Tai Bwo Wannai Cooperative in the middle of Tai Bwo Wannai Village. This appears to be dependant on if another player has sold one to the store or not.