Silkweed

Source
Silkweed is gathered from Silkweed herbalism nodes in Valley of the Four Winds on Pandaria. The nodes require herbalism skill 545 or greater in order to successfully gather. Silkweed can be found near water, in areas such as the Pools of Purity and the Gilded Fan, among others.

It can also be found on the Windless Isle of Jade Forest.

As an ingredient

 * Elixir of Mirrors (recipe)
 * Elixir of Perfection (recipe)
 * Elixir of Weaponry (recipe)
 * Flask of the Warm Sun (recipe)
 * Monk's Elixir (recipe)
 * Potion of the Jade Serpent (recipe)