Pyrrosia lingua, also called Tongue Fern or Shi Wei in Pinyin, is a less commonly used Chinese herb. And the leaves are its main medicinal part. As an endemic traditional Chinese medicine, the earliest known written record of its healing properties is the item in the "Shen Nong's Herbal Classic" (Shen Nong Ben Cao Jing). From the point of view of TCM, its main medicinal uses are characterized as inducing diuresis for treating stranguria and clearing heat for stanching bleeding. Today it is often used to treat acute and Chronic Nephritis, Pyelonephritis, Cystitis, urethritis, urinary stones, Bronchial Asthma, lung-heat induced cough, and so on.

This is a species of epiphytic fern that is a member in the family Polypodiaceae. However, in TCM it is not the only medicinal source of Shi Wei, which also refers to the dried leaves of Pyrrosia sheareri (Bak.) Ching, Pyrrosia petiolosa (Christ) Ching, Pyrrosia gralla (Gies.) Ching, Pyrrosia davidii (Bak.) Ching, and so on. And other common names of this herb include Tongue Fern, Pyrrosia Leaves, Folium Pyrrosiae, Japanese Felt Fern, and more. It grows wildly throughout China, especially in provinces of Taiwan, Zhejiang, Hubei, and Hebei. It can be harvested throughout the year. And the following process is to chop off the roots and rhizome, remove the impurities, wash away the sand and soil, dry in the sun or beside a fire, and cut into sections. Typically it is used raw medicinally.

Pyrrosia Lingua

As mentioned above, this herb can be used for many different ailments. So, what is its mechanism? Now let's take how it treats the upper urinary tract calculi as an example. This disease generally refers to the kidney or ureter stones, whose occurrence rate has increased in recent years, according to the reports. Its main clinical manifestations include activities-associated hematuria and pain, or renal colic caused by ureteral obstruction by stones. Currently, its leaf has been widely used in the treatment of the upper urinary tract calculi, thanks to its amazing ability of promoting diuresis to treat stranguria.

From point of view of Ben Cao Chong Yuan (The Esteemed Source of Materia Medica), pyrrosia herb bridges the intersection between the upward kidney essence and the downward lung essence. The upward water essence can help get though the upper and outside orifices; the descending lung qi can promote the circulation of waterway and thereby guide the urination back to normal.