From WoWWiki

Hunter Quests
Requirements
Petrified Leaf Black Sinew Blue Sinew	Quest Quest Quest
Rewards
The Bow The Staff The Quiver	Quest Quest Quest
The Demons
Artorius the Doombringer Klinfran the Crazed Simone the Seductress Solenor the Slayer	Strategy Strategy Strategy Strategy

The Ancient Petrified Leaf begins the first quest of the epic Hunter quest chain.

Source

This item is obtained from the Cache of the Firelord after defeating Majordomo Executus in the Molten Core.

External links