In Chinese folklore, it is believed that the root of he shou wu (何首烏,
Pleuropterus multiflorus) can, after a thousand years, transform into a human form, either as a child or an old person. It is also said that
Zhang Guolao, one of the
Eight Immortals, achieved immortality by consuming the essence of he shou wu. Two types of stories often revolve around the essence of he shou wu. In one version, a monk or Taoist acquires a human-shaped he shou wu and instructs a disciple to cook it. The disciple, tempted, secretly tastes it, becomes immortal, and disappears. In the other version, the essence of he shou wu takes on human form and accompanies a woman. Finding his behavior suspicious, the woman sews a thread into him. The following day, she traces the thread and finds it attached to a he shou wu root, from which a human shape is growing. ==Traditional medicine==