The Bencao gangmu 本草纲目 "Guidelines and details of materia medica" is China's most important traditional book on pharmaceuticals. It is 52 juan"scrolls" long and was written by the famous Ming period 明 (1368-1644) herbologist Li Shizhen (1518-1593), courtesy name Li Dongbi 李东壁, stylePinhu shanren 濒湖山人. He came from Qizhou 蕲州 (modern Qichun 蕲春, Hubei), and hailed from a family of physicians. His father Li Yanwen 李言闻, also called Li Yuechi 李月池, was a medical secretary in the Imperial Academy of Medicine (taiyi limu 太医吏目) and had written the books Sizhen faming 四珍发明, Aiyezhuan 艾叶传 and Douzhen zhengzhi 痘疹证治. Li Shizhen himself was an enganged student of his own father but did not have the ambition to achieve a career in the civil service. He nevertheless became a physician at the court of Zhu Yingxian 朱英{火+佥}, the Prince of Chu 楚, and later even administrative assistant in the Imperial Academy of Medicine (taiyi yuanpan 太医院判).

Li was a well-read person and had studied many kinds of books, from the obligatory Confucian Classics and the histories to the books of the masters and philophers, and, of course, specialized books on medicine and herbology. He therefore possessed an excellent overview of all statements on material medica in various types of literature. Yet Li Shizhen also gathered information from peasants, fishermen, travelers and craftsmen about drugs, their preparation and their effects, and was, as a physician, also experienced in the practical use of materia medica in clinical medicine. As a herb collector he was able to correct many errors and uncertainties in older books, for instance, the fact that the herb penglei 蓬虆 was in fact five different types of rubus. Old writings included many wrong statements about pharmaceuticals and it was therefore necessary to correct these errors and to add new, useful information. It was further necessary to add drugs that had not been known in earlier times. Li Shizhen took this task very seriously, visited experienced doctors and collected all kinds of information he was able to obtain. He had also prepared pictures of all pharmaceuticals that were later included in his book.

Li Shizhen evaluated more than 800 different sources, among these 276 medical books, and compiled his large book on material medica according to the pattern of the Song period 宋 (960-1279) pharmacopoeia Zhenglei bencao 类证本草. The compilation process consumed almost three decades, and the manuscript was revised three times. The book was finished in 1578 and the publication process began immediately, but Li Shizhen died before its completion.

The book is divided into 16 large classes of pharmaceuticals, according to their nature, that are divided into 62 sub-classes. Herbs, for instance, are divided into mountain herbs (shancao 山草), fragrant herbs (fangcao 芳草), marshland herbs (xicao隰草), creeping herbs (mancao 蔓草), poisonous herbs (ducao 毒草), aquatic herbs (shuicao 水草), stone herbs (shicao 石草), moss (taicao 苔类) and miscellaneous herbs (zacao 杂草). Inside the sub-classes the materia medica are arranged according from the smaller to the larger, the less valuable to the expensive drugs, and the simple to the complex.

The Bencao gangmu describes 1,892 different pharmaceutical objects, which is 374 more than in earlier pharmacopoeias. These additional herbs and objects mainly originate in regions that were formerly not part of the Chinese empire, especially the northwest and the southwest. Some drugs also come from abroad, like grapes (putao 葡萄), carrots (hu luobo 胡萝卜), pumpkins (nangua 南瓜), yam (ganshu 甘薯), Panax pseudo-ginseng (sanxi 三七), yasmin (moli 茉莉), tulips (yujinxiang 郁金香) or camphor (zhangnao 樟脑). The Zhenglei bencao provided a number of 1,479 drugs, and 39 drugs were included in sources from the Jin empire 金 (1115-1234) and the Yuan period 元 (1279-1368). The book is enriched with 1,109 illustrations of minerals, plants and other pharmaceutical objects. These illustrations are in most editions of the Bencao gangmu positioned at the beginning of the book. The illustrations were compiled by Li Shizhen's son Li Jianzhong 李建中 and painted by Li Jianyuan 李建元 and Li Jianmu 李建木. The quality of the paintings it not very superior, but they suffice to identify the plants.

The Bencao gangmu includes 11,096 recipes and treatment methods for various diseases. The large amount of drugs covered in the Bencao gangmu is owed to the principle of Chen Cangqi's 陈藏器 Bencao shiyi 本草拾遗 "Collected addenda to the pharmacopoeias" not to leave out any single information, but also to the Neo-Confucian attempt at investigating all things (ge wu 格物), like the Song and Yuan period physicians Zhang Yuansu 张元素 and Li Dongyuan 李东垣 had already done.

1,094 drugs are made of plants, which is more than half of all materia medica dealt with in the Bencao gangmu, and shows that "roots and herbs" (bencao 本草) were in fact the most important tools of an apothecary in ancient China. 276 drugs are made of minerals, and 444 out of parts of animals.
The pharmaceuticals are arranged according to their physical nature, beginning with anorganic substances, namely water (shui 水), fire (huo 火), earth (tu 土) and metals and minerals (jin shi 金石), which reflect four of the elements of the Five Processes 五行. The fifth element, wood (mu 木), is represented in the next part, divided into herbal plants (cao 草), grains (gu 谷), vegetables (cai 菜), fruits (guo 果), and trees (mu 木). This section is followed by six groups of moving creatures, namely worms, amphibia and reptiles (chong 虫), fishes (lin 鳞), animals with a shell, including turles (jie 介), birds (qin 禽), beasts (shou 兽), and man (ren 人). Another anorganic section is that of textiles and tools (fuqi 服器).

The first two juan include an introduction (xuli 序例) in which the seven basic methods (qi fang 七方) are described, the ten preparation methods (shi ji 十剂), the concepts of energy (qi 气), taste (wei 味), Yin and Yang 阴阳, rising and falling (shengjiang 升降), floating and submerging (fuchen 浮沉), the outwards phenomena (biaoben 标本) of the inner zang 脏 andfu 腑 organs, as well as the combination of drugs that mutually require each other, catalyse, avoid, "hate", "contradict" or even "kill" each other. The basic methods of application are described and what restrictions are to be observed. The introduction also explicates the functional quality of drugs that can be divided into "lords" (jun 君), "ministers" (chen 臣), and "assistants and runners" (zuo li 佐使). The introduction also includes an overview over pharmarcopoeias of earlier times and mentions 41 pharmaceutical books.

Juan 3 and 4 enumerate the most important standard pharmaceuticals that heal the 177 most oftenly occurring diseases and are easily to applicate. The main part of the book contains the detailed description of a huge number of pharmaceutical drugs. The description is systematically divided into eight parts, beginning with an analysis of the different names of drugs (shiming 释名), collected explanations (jijie 集解) about the places of origin, the genral appearance and the colleting methods of the drug, discussions of doubts (bianyi 辨疑) and corrections of errors occurring in older texts (zhengwu 正误), preparation methods (xiuzhi 修治), energy and taste (qiwei 气味), healing effects (zhuzhi 主治), and "enlightenments" (faming发明). All these parts quote extensively from older sources and are enriched by Li Shizheng's own remarks. An appendix chapter for each drug is commented regarding concrete treatment methods (fufang 附方).

Li Shizhen analysed many statements of older texts and found out many errors that he was able to rectify, like the fact thatPolygonatum odoratum (weirui 葳蕤) and Clematis apiifolia (nüwei 女萎) are two different plants, or that nanxing 南星 andhuzhang 虎掌 are the same drug, namely Pinellia temata. He also shifted ginger (jiangsheng 生姜) and Chinese yam (shuyu 薯蓣) from the herbs chapter to the chapter on vegetables, and betel (binlang 槟榔) and longans (longyan 龙眼) from the trees chapter to the fruits chapter. He discerned the proper orchids (lanhua 兰花) and Eupatorium fortunei (lancao 兰草), likewiseLilium lancifolium (juandan 卷丹) and proper lilies (baihe 百合), Polygonatum sibiricum (huangjing 黄精) and Gelsemium elegans (gouwu 钩吻), Calystegia sepium (xuanhua 旋花) and Alpinia japonica (shanjiang 山姜). Li Shizhen also renounced some older statements that were wrong in a pharmacological way. Quicksilver (shuiyin 水银), for instance, was thought to be non-toxic and was therefore consumed in great doses because people thought its consumption would lead to immortality. Ancient Daoist books like the Baopuzi 抱朴子 had an influence on medical treatises like the Mingyi bielu 名医别录 and theBencao shiyi, so that statements about the allegedly healthy application of gold (huangjin 黄金), realgar (As4S4, xionghuang雄黄), orpiment (As4S6, cihuang 雌黄) or cinnabar (HgS, dansha 丹砂) were recorded in pharmaceutical books. He also criticized superstitious beliefs like the theory of fish that grow out of grass seeds, or Cynomorium songaricum (suoyang 锁阳) growing in the earth out of horse sperm. On the other side, Li Shizhen clinged to some of these beliefs, like the theory that flies emerge out of rubbish or the superstitious belief that if a pregant woman does not eat meat, her baby will be born without lips.

The Bencao gangmu has a scientific value that can not be underestimated. It is therefore the most important pharmaceutical book in traditional China. It is a thorough and systematic compendium on Chinese parmacology until the mid-16th century. The book is arranged as guidelines (gang 纲) surrounding "meshes" (mu 目), the drug and its direct description constituting the guidelines, and its specifics corresponding to the "meshes". Other explanations see the 16 basic categories as "guidelines" and the subcategories of drugs as "meshes". Similarly, "genera" (like liang 粱 "millet") can be seen as guidelines, while "species" (like chiliang 赤粱 "red sorghum" and huangliang 黄粱 "yellow sorghum") are the "meshes". The description of individual drugs includes the origin of the materia, the place where it grows, lives or can be found, its appearance and collection method, as well as the preparation method of the required drug. Li Shizhen also explains experiences with the drug made by earlier physicians, and his own experiments. The entry of each drug is enriched by an appendix on treatment (fufang 附方), in which Li Shizhen explains 8,161 different recipes and treatment methods.

Li Shizheng's text is so comprehensive that the Bencao gangmu is not only a pharmaceutical book but can be used for informations on botany, zoology, chemistry and mineralogy. In the field of biology, for instance, Li Shizhen describes many details on lotus. He says that wild lotus has a red flowers, many stalks, but few roots, while the cultivated white lotus has precious roots. The species or kind of hehuan 合欢 has great heads, yeshuhua 野舒荷 opens at day and rolls in the petals at night, while shuilian 睡莲 submerges during the night. The kind of jinlian 金莲 has golden flowers, that of bilian 碧莲 green flowers, and xiulian 绣莲 flowers look like embroideries. In the field of geology or mineralogy he lists the places where petrol (shiyou 石油) is to be found in China, and explains that the local population stores the oil in jars and uses it as a fuel for lamps. The water lever in course terracotta jars can say a lot about the moisture of the air, as he explains, and can eventually predict rainfall. Li Shizhen gives an example to test the identity of chalcantithe (shidan 石胆, today called danfan 胆矾). He also believed that the brain was the organ of the "primordial spirit" (yuanshen zhi fu 元神之府), and not, as traditionally believed, the heart.

Except the Bencao gangmu Li Shizhen has also written a number of other medical books, like Pinhu maixue 濒湖脉学 (shortly called Maixue 脉学), Qijing bamai kao 奇经八脉考, Maijue kaozheng 脉诀考证, Wuzang tulun 五脏图论, Sanjiao kenan 三焦客难,Mingmen kao 命门考, Shiwu bencao 食物本草, Pinhu yi'an 濒湖医案 and Jijianfang 集简方. A biography of Li Shizhen can be found in the official dynastic history Mingshi 明史 (in the chapter of magicians, Fangjizhuan 方伎传), and in Gu Jingxing's 顾景星 collected writings Baimaotang ji 白茅堂集.