Zhu Su (8 October 1361 – 2 September 1425) was a medical scientist, botanist, author of Jiuhuang Bencao, and a prince of the Ming dynasty. He was the fifth son of the Hongwu Emperor and Empress Ma. In 1370, he was made the Prince of Wu, and in 1378, his title was changed to Prince of Zhou. He was assigned to Kaifeng in 1381.

Zhu Su was born on 8 October 1361, the fifth son of Zhu Yuanzhang (the future Hongwu Emperor) and his first wife, Lady Ma, according to official records.^[3] At the time, Zhu Yuanzhang was based in Nanjing and was a prominent leader in the Red Turban Rebellion. In 1368, he became the emperor of the Ming dynasty and quickly unified China under his rule. In May 1370, he granted the titles of princes (王) to seven of his sons, including Zhu Su who became the Prince of Wu (吳王). In 1374, the Emperor refused to allow Zhu Su to settle in Hangzhou, arguing that the revenue from Wu (Jiangnan) was crucial to the central government and should be under its direct control.^[3]

Zhu Su developed a close relationship with his fifteen-month-older brother, Zhu Di, despite their contrasting personalities.^[4] In 1376, he relocated to Fengyang in central China, where he engaged in military training with other princes. Two years later, his father bestowed upon him the title of Prince of Zhou (周王) and arranged for him to marry the daughter of General Feng Sheng, the military commander in Kaifeng, the capital of Henan. Upon reaching adulthood in 1381, Zhu Su moved to Kaifeng, where he held no official authority over the local administration, but his personal guard and large household, led by experienced advisors and officials, granted him significant influence. Alongside his father-in-law, Zhu Su oversaw the troops stationed in the province.^[3]

In 1389, Zhu Su secretly left Kaifeng for Fengyang to visit Feng Sheng,^[5] who had been condemned by the Emperor for his actions during a victorious battle against the Mongols in 1387.^[6] As a result, Zhu Su was banished to Yunnan in the southwest of the empire, but was actually held captive at the imperial court in Nanjing. His eldest son, Zhu Youdun, took over his household in Kaifeng and was officially named as Zhu Su's successor in 1391. Zhu Su was not permitted to return to Kaifeng until the end of 1391.^[7]

In 1398, the Hongwu Emperor died and was succeeded by his grandson, the Jianwen Emperor. The new government implemented a policy of "reducing the feudatories", resulting in Zhu Su being the first victim of this new policy.^[8] In the autumn of 1398, his second son Zhu Youxun accused him of planning a rebellion,^[7] leading to Zhu Su being imprisoned, stripped of his titles, and sent into exile in Yunnan.^[8] In August 1399, Zhu Di rebelled and after a three-year civil war, the Jianwen Emperor was defeated and Zhu Di took the throne as the Yongle Emperor. Zhu Su was able to return to Nanjing in 1402 and then to Kaifeng in 1403, resuming his previous position.^[7]

Although the Yongle Emperor provided him with double the usual princely stipend, transferred the revenues from trade taxes in Kaifeng to him, and bestowed high gifts,^[9] he was kept away from politics. As a result, Zhu Su turned his attention to science.^[10] He devoted himself to the study of botany and medicine, and in 1406, he published a botanical monograph titled Jiuhuang Bencao ("Famine Relief Herbal"), which described 414 edible wild plants.^[11] Most of these plants (276)^[10] were not mentioned in older herbals that focused solely on medicinal plants. The purpose of this book was to educate readers about edible plants that could be used in the event of crop failure and famine.^[11] In addition to this, he also published Puji fang ("Prescriptions for Common Benefit"), a collection of 61,739 medical prescriptions.^[12] Not only was he a talented writer, but he was also a skilled calligrapher.^[13]

In 1420, Zhu Su was summoned to Nanjing on charges of plotting a rebellion. He confessed to his crimes and was pardoned by the Emperor, but his personal guard was reduced to a minimum.^[14]

Zhu Su died on 2 September 1425.^[3] His eldest son, Zhu Youdun, was a prolific playwright who wrote over thirty plays in the zaju genre. He succeeded his father as the new Prince of Zhou.^[15] Zhu Su had a total of sixteen sons and ninthteen daughters. His descendants held the title of Prince of Zhou until the mid-17th century.