"Burmese temple murals of the moment of the Buddha’s enlightenment depict the seated Buddha being challenged by an army of demons summoned by the devil, Mara.  The Buddha’s hand touches the ground to summon the Earth Goddess who wrings out her hair to unleash a flood that sweeps away the demons.  A substantially different version of the story has Mara verbally challenging the Buddha: “Who knows that you have attained enlightenment?”  The Buddha touches the ground and calmly replies: “Mother Earth knows.”  Seated images are normally based on a lotus leaf, a symbol of spontaneous (i.e. divine) birth."

Cf.: http://seasiancrafts.com/spiritworld/buddha.htm