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 bio-diesel is that it can tolerate low rainfall (as little as 250 ml per year), far below what most food-crops require, thus reducing yet more their potential to compete. Some species of algae contain as much as 50% vegetable oil. Algae have very high growth rates compared to plants normally used to produce vegetable oil. Potentially algae could produce much more oil per area of land than current farming methods. So producing vegetable oil this way should result in less deforestation and less competition for food production land. One expert wrote: "As demonstrated here, microalgal biodiesel is technically feasible. It