Illustration of ' plum rain water' from Shiwu bencao (Materia dietetica), a dietetic herbal in four volumes dating from the Ming period (1368-1644). The identity of the author and artists is unknown. It contains entries on over 300 medicinal substances and is illustrated by almost 500 paintings in colour.
This illustration depicts the collection of plum rain water. Li Shizhen writes in Bencao gangmu (Systematic Materia Medica), Section on water, juan 5, in the entry on rainwater: With regard to meiyu (plum rain) or meiyu (mould rain), it is said that clothing or objects made wet by it develop black mould. Grain in Ear (Nangzhong, the 9th solar term, in early June) marks the arrival of the plum rains, and Slight Heat (Xiaoshu, the 11th solar term, in early July) marks their departure. In other words, the plum rains begin in the third [lunar] month and cease in the fifth [lunar] month. This is a period of hot, wet weather; it is close and muggy, and the high humidity produces torrential rain.' Under 'heavy rain' (fan yushui), in the same section of Bencao Gangmu, Li Shizhen cites Bencao shiyi (Supplement to the Materia Medica) by the Tang (618-907) pharmacologist Chen Zangqi: 'If plum rain wets clothing, it becomes black and mouldy. A peculiar liquid like lye rinses out of it. It can only be removed by washing in plum juice decoction; otherwise it cannot be removed'. The illustration conveys the idea that, in the season of plum rains, rainwater can be collected beneath plum trees, here shown in blossom.
The text states: To cure ringworm and scabies (xuanjie), and get rid of scars, one can wash in plum rain water. Liquor made with plum rain water matures rapidly. If clothing is made wet by plum rain water, it develops black mildew; mildew stains on garments can be removed by washing in plum juice decoction.
