生西域及大庾岭。蜀川两浙亦有之。叶如茅而软。面有纵纹。似初生棕榈状。其
根独茎劲直。二八月采根。曝干用。
味辛气热。有毒。（凡味之毒者必辛。气之毒者必热。）气味俱浓。可升可降。阴中阳也。
老人失溺无子。益阳道。助筋骨。明耳目。长精神。能通神强记。（命门之系。上通于心。
相火得补。则君火益自振摄故也。）益皮肤。治一切风气。（此属阳微而风之虚者）人身真阳
之火。即先天祖气。天非此火不能生物。人非此火不能有生。故真火一衰。则虚劳无子。阳
痿失溺。或风冷外侵。为腰脚挛痹不行。并不能生土。以致脾虚腹冷不能食。此药正入命门
。补火之不足。则诸证自除。筋骨自利。皮肤自益也。（仲淳）
〔论〕仙茅补命门真阳之火。夫阳以阴为主。经言出地者。阴中之阳。阳予之正。阴为
之主。苟阴胜而阳不足者。阳不能为阴之政。岂谓仙茅非适治之味哉。如阴虚而阳亢。阴又
不能为阳之主矣。此味固为禁剂。即阴阳俱虚之人。补阳亦必主以补阴。若漫言阳为阴先。
不反绝其化原乎。或曰桂附补阳。何以不切切致慎。之颐云。仙茅功齐雄附。但雄附起贞下
之元。此更深淫业之毒。斯语得之。
缪氏云。虽能补命门。益阳道。助筋骨。除风痹。然病因不同。寒热迥别。施之一误。
祸如反掌。况世人火旺致病者。十居八九。火衰成疾者。百无二三。凡水涸精衰。不能孕育。
老
〔修治〕以竹刀刮切。糯米泔浸。去赤汁。出毒后。方可用。
生长于西域及大庾岭。蜀川、两浙地区也有出产。叶片像茅草但质地柔软。叶面有纵向纹理。形状类似初生的棕榈树。它的根茎单一且强劲笔直。在农历二月和八月采集根部，晒干后使用。
味道辛，性质热，有毒。（凡是味道有毒的药材必定味辛，性质有毒的药材必定性热。）气味都非常浓厚，作用趋势既可上升也可下降，属于阴中之阳。
用于治疗老年人遗尿、无子嗣的情况，能补益阳气之道，帮助筋骨，使耳目聪明，增长精神，能够通神志、增强记忆力。（这是因为命门（肾间动气，生命之本）的脉络上通于心，相火（寄居于肝肾之火，推动生命活动）得到补益，则君火（心火，君主之官）自然更加振奋和摄持，所以如此。）还能滋养皮肤，治疗各种风气病证。（这属于阳气微弱而感受风邪的虚证）。人身真正的阳气之火，就是先天的祖气。天如果没有这把火就不能化生万物，人如果没有这把火就不能维持生命。所以真火一旦衰弱，就会导致虚劳、无子嗣、阳痿、遗尿，或者因风寒冷邪外侵，造成腰脚拘挛麻痹、行动不便，以及不能温煦脾土，导致脾虚腹部寒冷、不能进食。此药正好入命门经，补充火的不足，那么各种病症自然消除，筋骨自然强健，皮肤自然得到滋养。（出自陈实功/仲淳的观点）
〔论述〕仙茅能补益命门的真阳之火。然而，阳以阴为主宰，《内经》说“出地者”（指阳气从阴中生出），是阴中之阳。阳给予它正气，阴作为它的主宰。如果阴盛而阳不足，阳就不能成为阴的政令（主宰）。难道能说仙茅不是适宜治疗的药物吗？如果是阴虚而阳亢，阴又不能成为阳的主宰了。这种药确实属于禁忌药剂。即使是阴阳俱虚的人，补阳时也必须以补阴为主。如果说漫无边际地认为阳在阴之前，岂不是断绝了化生的本源吗？有人说桂枝、附子也能补阳，为什么不像对待仙茅那样谨慎呢？之颐说：仙茅的功效与雄黄、附子相当，但雄黄、附子能激发贞下之元（冬至一阳生），这里涉及更深层次的淫业之毒（指药性猛烈带来的副作用或因果报应层面的警示），这话是有道理的。
缪氏说：虽然仙茅能补命门，益阳道，助筋骨，除风痹，但是病因不同，寒热性质截然不同，施用错误，灾祸如反掌之间发生。况且世人因火旺致病的，十有八九；因火衰成疾的，百无一二。凡是肾水枯竭、精气衰败，不能孕育的情况……
〔炮制方法〕用竹刀刮切，用糯米泔水浸泡，去除红色的汁液，以去掉毒性后，方可使用。
Grows in the Western Regions and Dayu Ridge. It is also produced in Shuchuan and Liangzhe regions. The leaves resemble those of cogon grass but are soft. The leaf surface has longitudinal veins, resembling young palm trees. Its root is a single, strong, and straight stem. The roots are harvested in the second and eighth lunar months and used after sun-drying.
It tastes pungent and has a hot nature; it is toxic. (Generally, substances with toxicity in taste are necessarily pungent, and those with toxicity in nature are necessarily hot.) Both its scent and flavor are intense; its action can ascend or descend, belonging to "Yang within Yin."
It is used for elderly patients with urinary incontinence and infertility, benefiting the pathway of Yang, assisting the sinews and bones, clarifying the ears and eyes, and enhancing spirit and mental acuity. It can facilitate spiritual connection and improve memory. (This is because the system of Mingmen [Gate of Life, the source of original Qi] connects upward to the Heart. When Xianghuo [Ministerial Fire, which drives physiological activities] is supplemented, Junhuo [Monarch Fire, associated with the Heart] naturally becomes more vigorous and regulated, hence this effect.] It also nourishes the skin and treats various wind-related disorders. (These belong to deficiency patterns where Yang is weak and wind pathogens invade.) The true Yang fire in the human body is the ancestral Qi of the pre-heaven. Heaven cannot generate things without this fire, and humans cannot sustain life without it. Therefore, when true fire declines, it leads to consumptive diseases, infertility, impotence, and urinary incontinence. Or, due to external invasion of wind-cold, it causes spasms, numbness, and immobility in the waist and legs, and fails to warm the Spleen Earth, resulting in Spleen deficiency, cold abdomen, and anorexia. This herb precisely enters the Mingmer channel, supplementing the insufficiency of fire; thus, these symptoms will naturally resolve, the sinews and bones will become strong, and the skin will be nourished. (Viewpoint from Chen Shigong/Zhongchun)
[Discussion] Xianmao supplements the true Yang fire of Mingmen. However, Yang is governed by Yin. The Classics state that what emerges from the earth is "Yang within Yin." Yang provides its rectitude, while Yin serves as its master. If Yin is excessive and Yang is insufficient, Yang cannot govern Yin. Does this mean Xianmao is not a suitable remedy? In cases of Yin deficiency with Yang hyperactivity, Yin cannot serve as the master of Yang either. Thus, this substance is indeed contraindicated. Even in individuals with both Yin and Yang deficiency, when tonifying Yang, one must primarily tonify Yin. To casually claim that Yang precedes Yin would not it cut off the origin of transformation? Some ask: Guizhi Tang (Cinnamon Twig Decoction) and Fuzi (Prepared Aconite Root) also tonify Yang; why is such caution not emphasized for them? Zhiyi stated: Xianmao's efficacy rivals that of Xionghuang (Realgar) and Fuzi, but Xionghuang and Fuzi can revive the primordial Qi at the end of winter (Zhenxia). Here lies the deeper toxicity of licentious practices. This statement is insightful.
Mou stated: Although Xianmao can benefit Mingmen, aid the Yang pathway, strengthen sinews and bones, and dispel wind-bi, etiologies differ, and cold-heat natures are distinct. A misapplication brings disaster swiftly. Moreover, among people suffering from diseases caused by excess fire, eight or nine out of ten are affected; only two or three out of a hundred suffer from diseases caused by deficient fire. In cases of dried-up Kidney Water and depleted essence, unable to conceive...
[Processing Method] Scrape and slice with a bamboo knife. Soak in rice bran water (Nuomigan), remove the red juice to eliminate toxicity, and then it may be used.