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
Vegetable oils as alternative energy that yields 20% more oil than the standard variety. There is concern that the current growing demand for vegetable oil is causing deforestation, with old forests being replaced with oil palms. When land is cleared it is often burned, which releases large amounts of the greenhouse gas CO. Vegetable oil production would have to increase substantially to replace gasoline and diesel. With current technology such an increase in production would have a substantial environmental impact. In some poor countries the rising price of vegetable oil is causing problems. There are those that say using a food crop for fuel sets