生南海及雷州近海州郡。叶如桐。其花附干而生。侧敷如掌。形若金凤。枝干有刺。 刺
桐生山谷中。纹理细紧。而性喜拆裂。花繁如火。为夏秋荣观。（桐谱）
味苦。气平。气薄味浓。阴中之阳。入足太阴阳明经。 能行经络达病所。治腰脚不遂。
血
书治中风腰痛臂痛。行痹香港脚挛淋。 海桐皮禀木中之阴气以生。入血分去风杀虫。（仲淳
濒湖） 腰膝痛难忍。医以肾脏风毒攻刺。诸药莫疗。传信方。用海桐皮二两。牛膝芎 羌
活五加皮地骨皮各一两。甘草五分。薏苡仁二两。生地黄十两。并净洗。焙干。锉。以绵包
裹。入无灰酒二斗浸之。冬二七。夏一七。每早午晚空心。各饮一盏。长令醺醺。效。此方
不得添减。禁毒食。纾经汤。治气血凝滞。经络不行而臂痛。同白术当归赤芍等分服。 同
真川
〔论〕 海桐皮味苦气平。苦乃火味。平即金气。火金合而气乃化。气得化则血乃行。
故入血分而透经络也。其花色如火。乃入血之明征。其性喜拆裂。正缪氏所云阴中之阳。能
行经络。以善其血之达于周身者。能透经络。自于病所无不至。举上下内外而胥治之。第所
主治。类属下焦腰脚腿膝。岂其动而欲出。如多刺及喜拆裂之性。反在极阴极沉之所以奏功
乎。
缪氏云。凡因风湿湿热流注下焦腰膝为病。此药治之。若因阴虚血少火炽而得者。勿服。
〔修治〕 酒浸用。
产于南海及雷州半岛近海的州郡。叶片形状像梧桐树。花朵依附在树干上生长，侧面展开如同手掌，形态好似金凤凰。枝条和主干上有刺。
刺桐生长在山谷中，木质纹理细密紧实，但性质喜欢开裂。花朵繁茂如火，是夏秋季节观赏的佳品。（出自《桐谱》）
味道苦，气平。气薄味浓，属于阴中之阳。归入足太阴脾经和足阳明胃经。能够通行经络，直达病所。治疗腰脚活动不利。
书中记载治疗中风引起的腰痛、臂痛，以及行痹、香港脚（痛风）、筋脉拘挛等症。海桐皮禀受树木中的阴气而生，进入血分，能祛风杀虫。（出自缪希雍、李时珍）
对于难以忍受的腰膝疼痛，医生认为是肾脏风毒攻冲刺痛，各种药物无法治愈。《传信方》记载：用海桐皮二两，牛膝、川芎、羌活、五加皮、地骨皮各一两，甘草五分，薏苡仁二两，生地黄十两。全部洗净，焙干，切碎，用棉布包裹，放入无灰酒二斗中浸泡。冬季浸泡十四天，夏季浸泡七天。每天早、午、晚空腹时，各饮一盏，保持微醉状态，有效。此方不得随意增减剂量，禁止食用辛辣刺激性食物。
纾经汤，治疗气血凝滞、经络不通导致的臂痛。与白术、当归、赤芍等量服用。
【论述】海桐皮味道苦，气平。苦属于火的味道，平即代表金的属性。火与金结合，气化得以转化。气一旦转化，血液就能运行。因此进入血分并透达经络。其花色如火，是进入血分的明显证据。其性质喜欢开裂，正是缪氏所说的“阴中之阳”，能够通行经络，使血液善于通达全身。既然能透达经络，自然能到达病所，上下内外都能治疗。只是其主要主治部位多属下焦的腰、脚、腿、膝。难道是因为它动作向上向外，像多刺及喜欢开裂的性质一样，反而在极阴极沉的部位发挥作用吗？
缪氏说：凡是因风湿湿热流注下焦导致腰膝病变的，此药可以治疗。如果是因阴虚血少、虚火炽盛而得的病症，不要服用。
【炮制方法】用酒浸泡后使用。
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.