In Norse mythology, Yggdrasil (Old Norse Yggdrasill, IPA: ; the extra -l is a nominative case marker) is the "World Tree", a gigantic ash tree, thought to connect all the nine worlds of Norse cosmology. Sometimes it is called Mímameiðr or Lérað. According to mythology, Ásgard, Álfheim and Vanaheim rest on the branches of Yggdrasil. The trunk is the world-axis piercing through the center of Miðgarðr (often called Midgard), around which Jötunheim is situated, and below which lies Niðavellir, also called Svartálfheim. The three roots stretch down to Hel, Niflheim, and Muspelheim, although only the first world hosts a spring for Yggdrasil.