Choy sum facts for kids

Quick facts for kids Choy sum (Cantonese) Cai xin (Manadrin)
Choy sum plants, growing on a farm
Species	Brassica rapa var. parachinensis
Cultivar group	Chinensis, Pekinensis groups
Origin	China, before the 15th century
Cultivar group members	Many; see text.

Choy sum (also known as choi sum or choi sam in Cantonese, and cai xin in Mandarin) is a popular green leafy vegetable. It is often used in many kinds of Chinese dishes. This vegetable belongs to the mustard family, called Brassicaceae. Its scientific name is Brassica rapa var. parachinensis. The name "Choy sum" comes from Cantonese and means "heart of the vegetable." People also call it Chinese flowering cabbage because of its yellow flowers.

What Choy Sum Looks Like

Choy sum is a green leafy vegetable that looks a bit like gai lan. You can easily spot it because of its bright yellow flowers. Each flower has four yellow petals. The flowers grow on strong, upright stems. These stems are usually about 0.5 to 1 centimeter (0.2 to 0.4 inches) thick. They can grow to be 15 to 20 centimeters (6 to 8 inches) tall.

The leaves of choy sum are light to dark green. They are oval-shaped and have slightly jagged edges. Unlike regular cabbage, choy sum leaves do not form a tight, round head. After flowering, small fruits can grow. These fruits contain tiny, round, brown or black seeds. One fruit can hold many seeds, from 4 to 46!

How Choy Sum Grows

The height of a choy sum plant can change a lot. It can be anywhere from 10 to 40 centimeters (4 to 16 inches) tall. This depends on where it is growing and what type of choy sum it is. The plant usually starts to flower when it has about 7 or 8 leaves. This is also when it reaches about 20 centimeters (8 inches) in height.

Most of the plant's roots stay close to the surface. They usually grow within 12 centimeters (about 5 inches) deep in the soil. The roots also spread out about 12 centimeters (about 5 inches) from the plant. Choy sum grows best in soil that is not too acidic or too alkaline. It prefers a pH level between 5.6 and 7.5.

Choy sum is usually an annual plant. This means it completes its whole life cycle in one year. It is a herbaceous plant, which means it has soft, green stems, not woody ones like a tree.

Gallery

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  Typical choy sum fresh from field in Hainan

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  Choy sum variety in Thailand, called phàk Kwangtûng (lit: Cantonese cabbage; cabbage of Guangdong)

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  Purple choi sum, a choy sum variety in Hong Kong

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  Cooked choy sum in soy sauce in Hong Kong