Brassica campestrisL.chinensis(L) Makino var.communis Tsen et lee
Other names: Naipetsai, Nai Pe Tsai, Nai Bai Cai (Naibaicai ), Nai Yu Bok, Nai You Bai Cai ( Naiyou Baicai ), Baby White (Stem ) Pak Choy, Dwarf White (Stem ) Pak Choy, Dwarf Choy Sum, Choy Sum.
*White Pak Choy: Large type and is popular group in North America.
*Baby Pak Choy: Baby type and is the most popular group of white Pak Choy. The plant is dwarf, typically 10~15cm (4~6"). The petioles are spoon-shaped, pure white, short and succulent. The leaves are dark green and wrinkled. It is also called Nai Bai Cai, Nai You Bai Cai.
*Mini Pak Choy: Mini type, an extra dwarf white pak choy. The plant is typically 5~10cm (2~4"). Also called Baby Nai-Pe-Tsai, Baby Nai Yu Bok, Extra Dwarf White Pak Choy, Nai-Pe-Miao,Nai Bai Miu.
*Taiwan Pak Choy is another group. It's also called Wa Wa Tsai and Sweet Pak Choy in some areas.