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(From *Wu Pu Bencao*)

[Names] Cai (from *Shiyi*), Siye Cai (Four-Leaf Vegetable, from *Zhiyan*), Tianzi Cao (Field-Character Grass).

Li Shizhen states: "Ping" was originally written as "𦰩". The *Zuo Zhuan* records: "Vegetables such as ping, fan, yun, and zao can be offered to spirits and gods, and presented to kings and nobles." Thus, "𦰩" carries the meaning of a guest, hence the character includes the component "bin" (guest). This plant has four leaves that join together, forming a cross shape when broken in the middle; therefore, it is commonly called Siye Cai (Four-Leaf Vegetable), Tianzi Cao (Field-Character Grass), or P Tongqian (Broken Copper Coin), all names derived from its shape. Various pharmacopoeias have annotated "ping" as water duckweed, likely due to the phonetic similarity between the characters "ping" (苹) and "ping" (萍). According to rhyme books: "Ping" (苹) belongs to the Zhen rhyme, pronounced with the initial 'pu' and final 'zhen'; "Ping" (萍) belongs to the Geng rhyme, pronounced with the initial 'pu' and final 'jing'. Since the fanqie (reverse spelling) pronunciation differs, they refer to different substances. Following *Wu Pu Bencao*, this entry is listed separately here.

[Collected Explanations] Wu Pu says: Water duckweed, also known as Shuilian, grows on the surface of ponds and marshes. The leaves are small and round, one leaf per stem, with roots penetrating the bottom. It flowers white in May. Harvested in March and dried in the sun.

Tao Hongjing says: The large duckweed found in water bodies flowers white in May; it is not the duckweed found in ditches and canals. The specimen obtained by the King of Chu while crossing the river is indeed this type.

Su Gong says: There are three types of duckweed: the large one is called Ping (苹), the medium one is called Xing (荇); their leaves are similar and round. The smallest is the floating duckweed on the water surface.

Zang Qi says: The leaves of Ping (苹) are round, about one cun wide. There is a spot underneath the leaf, resembling foam. Also known as Cai (菜). Dried, it can be used medicinally. The small duckweed is the kind found in ditches.

Yu Xi notes: The *Erya* states: "Duckweed is [character]. The large ones are called Ping (苹)." Furthermore, the *Book of Songs* says: "Where to gather Ping? By the stream bank." Lu Ji's commentary states: The coarse/large ones are called Ping (苹), the small ones are called Ping (萍). They begin to grow in late spring. They can be mixed with flour and steamed as food, or pickled in sour wine. Currently, physicians rarely use this specific Ping (苹), using only the small floating duckweed instead.

Li Shizhen says: Ping (苹) is the Four-Leaf Vegetable. Its leaves float on the water surface, and its roots connect to the bottom. Its stems are thinner than those of [character] and Xing. The leaves are as large as a fingertip, green on the upper surface and purple on the lower, with fine veins, somewhat resembling the leaves of Cassia obtusifolia (Ma Ti Jue Ming). Four leaves combine into one, forming a cross in the center. Small white flowers bloom in summer and autumn, hence it is called Bai Ping (White Ping). Its leaves cluster like duckweed, which is why the *Erya* refers to the large variety as Ping (苹). The *Lüshi Chunqiu* states: "Among delicious vegetables, there is the Ping of Kunlun." This refers to this plant. The *Han Shi Waizhuan* states that what floats is [character], and what sinks is Ping (苹). Xian Xian states: Those with white flowers are Ping (苹), those with yellow flowers are Xing (荇), which is also Jinlian (Golden Lotus). Su Gong states: The large ones are Ping (苹), the small ones are Xing (荇). Yang Shen's *Zhiyan* states that the Four-Leaf Vegetable is Xing. Tao Hongjing states that what the King of Chu obtained was Ping (苹). None of these statements are definitive. This is likely because they did not observe closely, relying merely on speculation from texts. I, Li Shizhen, collected and examined them one by one, and grasped their true nature. The leaves are one to two cun in diameter; those with one notch and rounded like a horse hoof are [character]. Those similar to [character] but slightly sharper and longer are Xing. Their flowers come in both yellow and white varieties. Leaves four to five cun in diameter, resembling small lotus leaves, flowering yellow, and bearing fruit resembling small glutinous rice dumplings, are Pengpeng Cao (Pongpon Grass). The "Ping Shi" (Duckweed Fruit) obtained by the King of Chu is the fruit of this Pengpeng Cao. Four leaves combining into one, shaped like the character 'field' (田), are Ping (苹). Such distinction makes it naturally clear. Additionally, Mr. Xiang stated: White Ping grows in water, Green Ping grows on land. According to current knowledge, Tianzi Cao (Field-Character Grass) has aquatic and terrestrial varieties. The terrestrial variety often grows in damp, muddy areas of rice fields. Its four leaves unite, identical to White Ping. However, the stems grow above ground, three to four cun high, and are inedible. Alchemists use it to calcine sulfur, condense cinnabar, and boil mercury, calling it Shuitian Weng (Water Field Old Man). The "Green Ping" mentioned by Mr. Xiang is likely this. Some mistake Green Ping for aquatic grass, which is an error.

[Flavor and Properties] Sweet, Cold, Slippery, Non-toxic.

[Therapeutic Actions] Treats sudden high fever, directs downward rebellious water qi, promotes urination (from *Wu Pu*). Crushed and applied externally treats hot sores. Juice drunk internally treats snake venom that has entered the abdomen. Dried and powdered equally with Trichosanthis Fructus (Gualou), formed into pills with human milk and taken orally, stops Xiao Ke (Wasting-Thirst syndrome) (from Zang Qi). Eating it cures exhaustion/overwork (from *Shan Hai Jing*).