They are found on Doogle Bushes on the ground south of Gertrude's house (just west of Varrock), in Feldip Hills (directly west of the swamp where you can fill your ogre-bellows and catch the toads during the Big Chompy Bird Hunting quest), and east of Rellekka (near the Golden Apple Tree). Doogle leaves are also used as a writing surface by the gnomes, particularly for mapping. These "Doogle Maps" are likely a reference to Google Maps.