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It grows in the southern seas and coastal prefectures near Leizhou. The leaves resemble those of the Paulownia tree. The flowers grow attached to the trunk, spreading sideways like a palm, with a shape resembling a golden phoenix. The branches and trunk have thorns.

*Erythrina variegata* (Coral Tree) grows in mountain valleys. Its wood grain is fine and tight, but its nature tends to split. The flowers are abundant and fiery, making it a splendid sight for summer and autumn. (*Tong Pu*)

Bitter in taste, neutral in qi. The qi is thin while the flavor is strong; it belongs to yin within yang. It enters the Foot Taiyin Spleen Meridian and the Foot Yangming Stomach Meridian. It can circulate through the meridians and reach the site of disease. It treats immobility of the waist and legs.

Medical texts record its use for treating lower back pain and arm pain caused by wind-stroke, as well as Bi syndrome characterized by wandering pain, Hong Kong foot (gout), and tendon spasms. *Hai Tong Pi* (Sea Hemp Bark) is born from the yin qi of trees, enters the blood aspect, dispels wind, and kills parasites. (Miao Zhichun, Bencao Gangmu)

For unbearable pain in the waist and knees, where physicians attribute the condition to kidney wind-toxin attacking and stabbing, and other medicines fail, *Chuan Xin Fang* prescribes: 2 liang of *Hai Tong Pi*, 1 liang each of *Niu Xi* (Achyranthes Root), *Xiong* (Ligusticum Rhizome), *Qiang Huo* (Notopterygium Rhizome), *Wu Jia Pi* (Acanthopanax Bark), and *Di Gu Pi* (Cortex Lycii), 5 fen of *Gan Cao* (Licorice Root), 2 liang of *Yi Yi Ren* (Coix Seed), and 10 liang of *Sheng Di Huang* (Rehmannia Root). All ingredients are thoroughly washed, dried by baking, and chopped. They are wrapped in cotton cloth and soaked in 2 dou of unadulterated wine. Soak for 14 days in winter and 7 days in summer. Drink one cup on an empty stomach every morning, noon, and evening, maintaining a slightly intoxicated state. This is effective. Do not alter the dosage of this prescription. Avoid spicy and stimulating foods.

*Shu Jing Tang* (Meridian-Relaxing Decoction) treats arm pain caused by stagnation of qi and blood and obstruction of the meridians. Take it in equal parts with *Bai Zhu* (Atractylodes Rhizome), *Dang Gui* (Angelica Sinensis Root), and *Chi Shao* (Red Peony Root).

[Discussion] *Hai Tong Pi* is bitter in taste and neutral in qi. Bitterness corresponds to the fire element, and neutrality corresponds to the metal element. When fire and metal combine, the qi transforms. Once the qi transforms, the blood circulates. Therefore, it enters the blood aspect and penetrates the meridians. Its flower color being like fire is clear evidence of its entry into the blood. Its tendency to split aligns with Miao’s description of "yin within yang," enabling it to circulate through the meridians and facilitate the smooth distribution of blood throughout the body. Since it can penetrate the meridians, it naturally reaches all disease sites, treating conditions both above and below, inside and outside. However, its primary indications are mostly located in the lower jiao—waist, legs, feet, and knees. Is it because its upward and outward movement, akin to its thorny and splitting nature, allows it to exert efficacy in the deepest, most yin, and sinking regions?

Miao states: For diseases of the waist and knees caused by the flow and accumulation of wind-dampness or damp-heat in the lower jiao, this herb is suitable. However, if the condition arises from yin deficiency, blood insufficiency, and blazing deficient fire, it should not be taken.

[Processing Method] Soak in wine before use.