Brassicaceae greens, Savoy, kohlrabi, and gai lan ("Brassica oleracea"), turnip, napa cabbage, bomdong, bok choy and rapini ("Brassica rapa"), rocket salad/arugula ("Eruca sativa"), garden cress ("Lepidium sativum"), watercress ("Nasturtium officinale") and radish ("Raphanus") and a few spices like horseradish ("Armoracia rusticana"), "Brassica", wasabi ("Eutrema japonicum"), white, Indian and black mustard ("Sinapis alba", "Brassica juncea" and "B. nigra" respectively). Vegetable oil is produced from the seeds of several species such as "Brassica napus" (rapeseed oil), perhaps providing the largest volume of vegetable oils of any species. Woad ("Isatis tinctoria") was used in the past to produce a blue textile dye (indigo), but
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.