Draconis Sanguis (traditionally the red resin of Daemonorops draco Bl., a rattan palm; the same commercial name is also applied to unrelated resins from Dracaena and Croton species)
Nature and flavour. Sweet, salty, neutral. Heart and Liver systems.
A red resin, and one of the few items in the materia medica whose name is pure theatre: 血竭 is dragon's blood, and the resin is exuded by the fruit of a rattan palm after it is bruised or heated. Classical texts describe it as invigorating blood and settling pain, transforming stasis and checking bleeding, and engendering flesh and closing sores; it is recorded externally for wounds, for sores and ulcers that will not close, and for bleeding from a wound, and internally for the pain of blood stasis. Resins of this kind have also been used outside medicine as colouring matter and as a varnish. The identification is the awkward part, and honest entries should say so: several botanically unrelated resins have been traded as dragon's blood — from Daemonorops, from Dracaena species, and from Croton lechleri in South America — and they are different articles with different constituents. What a given sample actually is depends on the supply chain it came through.
性味归经。甘、咸，平。归心、肝经。
一份红色树脂，也是本草中少数名字本身就是一场戏的药材：血竭即龙血，树脂由棕榈科藤本植物果实受创或受热后渗出。古籍记载活血定痛、化瘀止血、生肌敛疮，外用治跌打损伤、久不敛口的疮疡溃疡与创伤出血，内服用于瘀血疼痛。这类树脂在医药之外也作着色料与清漆使用。麻烦出在品种认定上，诚实的条目应当说明：有若干植物学上毫不相干的树脂都曾以龙血之名流通 —— 来自黄藤属、来自龙血树属、以及南美的 Croton lechleri —— 它们是不同物品，成分也不同。手头那一份究竟是什么，取决于它经过哪条供应链。
本批中性质最温和的一味，但仍然不宜在无专业意见的情况下自用。它是活血药，古籍禁忌明确：孕期及无瘀血者不宜 —— 文本写得很清楚，它不是出血的通用补药。内服不属于自用范畴，此处内服用途按传统记载记录。外用方面，树脂类是公认的接触性致敏物，涂抹处出现皮疹即应停用而非继续。最要紧的提醒适用于任何敷在伤口上的东西：久不愈合的伤口本身就是信息。小腿或足部长期不愈的溃疡可能是血管性、神经性或其他需要评估的问题，用树脂敷上只会推迟诊断。非正规渠道所购可能并非此处所述的树脂，或经染色处理；应按可追溯的品种买，而不是看外观。孕期与哺乳期避免使用。