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(Bai Xian Pi / Cortex Dictamni) possesses a penetrating nature and dispels wind-dampness. Its qi is cold and agile, its flavor bitter and nature drying (it is drying because it promotes water metabolism). It enters the Spleen and Stomach channels to drain damp-heat, and concurrently enters the Bladder and Small Intestine channels. It unblocks water passages, opens joints, and benefits the nine orifices.

It is a key herb for treating various types of jaundice and wind-bi syndrome (a single-herb decoction of Bai Xian Pi treats postpartum wind pathogen. Li Shizhen stated: Contemporary physicians only apply it to dermatology, which is superficial).

It also treats wind-induced sores, scabies, tinea, and swelling and pain in the female vagina (caused by damp-heat invading the Kidney and Bladder due to deficiency).

(Bi Xie / Rhizoma Dioscoreae Hypoglaucae) possesses a penetrating nature, dispels wind-dampness, and tonifies the Lower Jiao. Its flavor is sweet and bitter, and its nature is neutral. It enters the Foot-Yangming and Foot-Jueyin channels (Stomach and Liver). It dispels wind and removes dampness to stabilize the Lower Jiao (the Yangming channel governs flesh and is associated with dampness; the Jueyin channel governs sinews and is associated with wind), tonifies Liver deficiency (by dispelling wind), strengthens sinews and bones (when wind-dampness is removed, sinews and bones become firm), benefits essence, and brightens the eyes.

It treats bi syndrome caused by wind-cold-dampness, chronic lower back pain with a sensation of cold, old blood stagnation in joints, retained water in the Bladder, impotence, urinary incontinence, penile pain, and seminal emission/turbid urine, as well as hemorrhoids and malignant sores (these conditions all result from damp-heat flowing into the Lower Jiao from the Yangming channel; Bi Xie can separate the clear from the turbid. Ancient formulas include Bi Xie Fen Qing Yin. Shi Guoxin said: If one wishes to promote yang, one must first nourish the sinews. If one wishes for clear urination, one must first subdue Liver fire. The *Wanjin Huming Fang* states: When a person suffers from frequent urination with unbearable pain during voiding, this disease is necessarily due to constipation and blockage in the Large Intestine, causing fluid to flow only into the Small Intestine, further depleting the Large Intestine. This may lead to severe symptoms such as fever, restlessness, and thirst. The root cause is indulgence in alcohol and sex, or excessive consumption of spicy, hot, meaty, or greasy foods, accumulating heat toxins. Rotting matter and blood stasis invade the Small Intestine due to deficiency, causing pain during urination. This frequency and pain differ from strangury, which is characterized by obstruction and pain. One should use 1 liang of Bi Xie, stir-fried with salt water, ground into powder, taken 2-3 qian per dose, to redirect the water pathway to the Large Intestine. Simultaneously, wash the anus frequently with green onion soup to ensure qi circulation, thereby reducing frequency and pain. The Kidney has two orifices; strangury originates from the urinary orifice, while turbidity originates from the seminal orifice).

There are yellow and white varieties. The yellow variety is long and hard (*ying*), while the white variety is hollow and soft; the soft variety is superior. Coix Seed (*Yi Yi Ren*) serves as its assistant. It is incompatible with Da Huang, Chai Hu, and Qian Hu. Tea and vinegar are contraindicated (Li Shizhen noted: Bi Xie, Ba Qia, and Tu Fu Ling have different appearances but similar therapeutic effects; could they be species of the same genus? Bi Xie roots are slender and pale white; Ba Qia roots are tuberous and yellow).