An Interest In Botany Quest/Spoiler

Required Equipment

 * Obsidian Knife
 * Rope
 * Shovel
 * Levitate or 6 Parcels/Crates

Method

 * Visit Rabaz in Farmine and ask him for a mission.
 * Go to the room left of him and take his Botany Book.
 * You have to find 2 plants and use your Obsidian Knife on them. Both can be found in the Zao Wailing Widow Cave. Go to this cave and head north-east on the first floor. You will find a part of the cave which is corrupted and full of diseased plants. Find the 2 plants and use them to get your samples (you won't get anything in your backpack, just using is enough). Alternately you can find one of the plants in the north-western gnarlhound cave.
 * Go back to Rabaz to claim your reward.