Nourishes yin (femanine or dark), tonify (increases the avaiable energy to) the kidneys, enriches essence, and strengthens the marrow.  It can be used for deficiency of true yin, with symptoms including soreness and weakness of the lumbar region and knees, dizziness and vertigo, deafness and insomnia, spermatorrhea and premature ejaculation, spontaneous sweating and night sweats, dry mouth and tongue, red tongue with scanty coating, and thin pulse.

功用：滋阴补肾、填精益髓，可用于真阴不足之证，其症见：腰膝酸软，头晕目眩，耳聋失眠，遗精滑泄，自汗盗汗，口燥舌干，舌红少苔，脉细。