Choy sum Choy sum Choy sum (also spelled choi sum or "Cai Xin" in modern Pinyin) is a leafy vegetable commonly used in Chinese cuisine. It is a member of the genus "Brassica" of the mustard family, Brassicaceae ("Brassica rapa" var. "parachinensis" or "Brassica chinensis" var. "parachinensis"). Choy sum is a transliteration of the Cantonese name (), which can be literally translated as "heart of the vegetable". It is also known as Chinese Flowering Cabbage. Choy sum is a green leafy vegetable similar to gai lan, and can be characterized by the distinct yellow flowers which it bears. Each flower has four
Fat choy This may be one reason why some commercially available fat choy has been found to be adulterated with strands of a non-cellular starchy material, with other additives and dyes. Real fat choy is dark green in color, while the counterfeit fat choy appears black. The last two syllables of this name in Cantonese sound the same as another Cantonese saying meaning "struck it rich" (though the second syllable, "coi", has a different tone) -- this is found, for example, in the Cantonese saying, ""Gung1 hei2 faat3 coi4"" (恭喜發財, meaning "wishing you prosperity"), which is often proclaimed during Chinese New Year.