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Water Duckweed (Shuiping)

Pungent, sour, cold, non-toxic. It primarily treats sudden fever accompanied by body itching, eliminates water qi (fluid retention), overcomes alcohol intoxication, promotes the growth of beard and hair, stops xiaoke (wasting-thirst syndrome), and directs rebellious qi downward. Used for bathing, it generates hair. Long-term consumption lightens the body. It is also known as Shuihua (Water Flower), Shuibai (Water White), and Shuisu (Water Perilla). It grows in the ponds and marshes of Leize. It is harvested in the third lunar month and dried in the sun.

Tao Hongjing stated: This is the large duckweed found in water, not the modern Fupingzi (smaller variety or seeds of duckweed). *Yaolu* states: It flowers in the fifth lunar month with white flowers. Thus, it is not the kind growing in ditches and canals today. What King Chu obtained while crossing the river was not this specific substance. *Tang Ben Zhu* states: There are three types of water duckweed; the large one is called Ping (Marsilea quadrifolia). In the water, there is also Xingcai (Nymphoides peltata), which is similar but has round leaves. The small floating duckweed on the water surface treats fire sores. I now refer to Chen Cangqi's *Bencao*: There are three types of water duckweed; the large one is called Ping, with leaves round and broad about one cun, having a spot resembling water foam underneath the leaf, also named Xingcai. Dried, when combined with equal parts of Gualou (Trichosanthes fruit) and formed into pills using human milk, it treats xiaoke. Crushed and juiced for drinking, it treats snake venom entering the abdomen, and can also be applied to hot sores. The small Fupingzi grows in ditches and canals. Powdered and applied to the face, or juice taken orally, it treats edema and promotes urination. Additionally, for poisoning, take Fupingzi, dry it in the sun, powder it, and administer one Fangcunbi (a measure equivalent to a square inch) with wine. Also made into an ointment to promote hair growth. *Ben Jing* refers to Shuiping, which should be the smaller type. Minister Yuxi et al. respectfully note that *Erya* states: Ping, Xing. The larger one is called Ping. Commentary: Floating plants in water, referred to as Xing in Jiangdong. Lu Ji's *Maoshi Yishu* states: The coarser and larger ones are called Ping, the smaller ones are called Xing. They begin to grow in late spring, can be mixed with flour and steamed as vegetables, or pickled in sour vinegar to accompany wine. Rihua Zi states: It treats heat-toxin wind, heat diseases, heat mania, swelling and toxins, scalds and burns, and wind-rash.

*Tujing* states: Water duckweed grows in the marshes of Leize, and is now found in streams and creeks everywhere. This is the large duckweed in water, with leaves round and broad about one cun, with Xingcai underneath the leaf. *Erya* calls it Ping. The larger one is indeed called Ping. The *Zhou Nan* poem says: "Where to gather Ping." Lu Ji refers to it as Ping. It begins to grow in late spring, can be mixed with flour and steamed as vegetables. It can also be pickled in sour vinegar to accompany wine. Harvested in the third lunar month and dried in the sun. Su Gong states: There are three types: the large one is called Ping; the medium one is Xingcai, which is the Fu Kui mentioned below; the small one is the floating duckweed on the water surface, which is the kind growing in ditches and canals. Large Ping is rarely used in current medical prescriptions. Floating duckweed is commonly used by folk doctors to treat epidemic heat diseases and can induce sweating, demonstrating efficacy. One prescription uses one liang of Fuping grass (harvested on the 15th day of the fourth lunar month), Mahuang (Ephedrae Herba) with nodes and roots removed, Guixin (Cinnamomi Ramulus), and Pao Lie Qu Qi Pi Fuzi (Prepared Aconiti Lateralis Radix) each half liang. These four ingredients are crushed, finely sifted, and two qian are taken per dose. With one zhongzhan of water and half fen of fresh ginger, decoct until six fen remains. Take warm with the dregs at any time; recovery occurs upon sweating. Another prescription: To treat severe diseases with sores all over the body, take strong decoction of water-floating duckweed, soak and bathe for half a day; this is often effective. This prescription is very ancient and unique. *Shenghui Fang*: To treat fine pimples appearing on the faces of youths, crush Fuping and apply it; drinking a small amount of juice is also good. Another prescription: For early-stage Faback (carbuncle on the back) with toxic swelling, heat, redness, and ulceration, crush and mix with egg white for topical application; this is effective. *Qianjin Fang*: To treat water toxicity, characterized by coldness in the fingers and toes, extending to knees and elbows, use sun-dried Fuping, take one Fangcunbi, and recover. *Qianjin Yi*: To treat difficult urination due to stagnation of water qi in the bladder, use sun-dried Fuping powdered and administered. Dry in shade, burn as smoke to repel mosquitoes. Also, to treat xiaoke, administer Fuping juice. *Zimu Milu*: For heat-toxin, crush Fuping and apply the juice thoroughly. Song of High Official Gao harvesting duckweed: Not in the mountains, not on the shore, harvest me in the middle of the seventh lunar month. Selecting between paralysis wind and mild wind, even slight breezes do not count. Three pills in bean-dripping wine will cause sweat even on an iron head.