Polygala tenuifolia is an herb in the family Polygalaceae

Polygalaceae

The Polygalaceae or Milkwort family is a family of flowering plants in the order Fabales. They have a near-cosmopolitan range, with about 17 genera and 900–1,000 species of herbs, shrubs and trees...

 which is hardy to USDA Zone 6.

Medicinal uses

Yuan Zhi is used primarily as an expectorant

Mucolytic agent

Mucokinetics are a class of drugs which aid in the clearance of mucous from the airways, lungs, bronchi, and trachea. Such drugs can be further categorized by their mechanism of action.* expectorants* mucolytic agents...

. It is one of the 50 fundamental herbs used in traditional Chinese medicine

Traditional Chinese medicine

Traditional Chinese Medicine refers to a broad range of medicine practices sharing common theoretical concepts which have been developed in China and are based on a tradition of more than 2,000 years, including various forms of herbal medicine, acupuncture, massage , exercise , and dietary therapy...

, where it is called yuan zhi .

Medical study

A randomized, double-blind, placebo-controlled, parallel-group study of the extract of dried roots of Polygala tenuifolia in healthy adults produced memory-enhancing effects.
A similar trial with elderly humans also found significant cognitive improvement.

A number of in vitro

In vitro

In vitro refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments...

experiments have examined the use of the herb in Alzheimer's disease, memory disorder, depression, amnesia, cognitive defects, neurotoxicity, degenerative disease,and dementia among others. Results have been encouraging.