- You will get 1000 Seeds of Oriental Mustard (Chinese Mustard, Gai Choy), Brassica Juncea Vegetable Seeds. - Genus: Brassica. - 1,000 Seeds of Oriental Mustard (Chinese Mustard, Gai Choy), Brassica Juncea. - This popular, tasty mustard green is easy and quick to grow. Leaves are broad and green color with thick and wide petioles. A vigorous growing, semi-heading plant that is one of the main types of Chinese mustard grown. Pungency increases with maturity. - Chinese mustard greens, also known as gai choy in cantonese or 芥菜 [jiè cài] in Mandarin, is a type of mustard plant. Chinese mustard greens are common green vegetables served as a side dish or appetizer. They are full of nutrition and low in carb.