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Brassica rapa Caisin Group [cai xin]


Brassica rapa Caisin Group [cai xin]

Family Name: Brassicaceae (Cruciferae)
Synonyms: Brassica chinensis var. parachinensis, Brassica parachinensis, Brassica rapa subsp. pekinensis
Common Name: Cai Xin, Sawi, Chinese Flowering Cabbage, Choy sum, 菜心


Family Name
Genus Epithet
Species Epithet
Infraspecific Epithet
Common Names

Classifications and Characteristics

Plant Division Angiosperms (Flowering Seed Plants) (Dicotyledon)
Plant Growth Form Herbaceous Plant
Lifespan (in Singapore) Annual
Mode of Nutrition Autotrophic
Maximum Height 20 cm to 30 cm


Native Distribution China
Native Habitat Terrestrial
Preferred Climate Zone Tropical, Sub-Tropical / Monsoonal, Highland / Montane
Local Conservation Status Non-native (Horticultural / Cultivated Only)

Description and Ethnobotany

Growth Form Herbaceous annual, fast-growing up to 0.5m tall.
Foliage Rosette leaves few, usually with only 1-2 leaf layers and with a 2/5 phyllotaxy, long petioled, bright green, stem leaves not clasping, finely toothed when young; lower stem leaves ovate to nearly orbicular; central stem leaves ovate to lanceolate to oblong with long and narrow, grooved petioles that are sometimes obscurely winged; upper stem leaves gradually passing into narrow bracts. 
Stems Usually less than 1cm in diameter, profusely branched. 
Flowers Inflorescence a terminal raceme, elongating when in fruit; cream-colored to very light-yellow.
Fruit Slender, up to 5cm long with slender brief beak, containing 10-20 seeds. Seed globose, about 1mm in diameter, smooth with faint raphal line. 
Cultivation Fast growing annual that thrives in fertile and well-drained soil. It takes about 40-80 days from sowing to first harvest. When the plants are young, provide light shade to prevent the leaves from being burned. Mature plants can take full sun and should be mulched to keep the roots cool. Slight tolerant to water deficit but susceptible to waterlogging.
Ethnobotanical Uses Edible Plant Parts : Edible Leaves, Edible Flowers
Food (Fruit or Vegetable): Choy sum is one of the most popular vegetables among the Chinese. The flowering shoots and younger leaves of choy sum are used in salads or stir fried, lightly boiled or steamed. 

Landscaping Features

Landscape Uses Small Gardens, Flowerbed / Border, Container Planting
Thematic Landscaping Economic Garden

Fauna, Pollination and Dispersal

Pollination Method(s) Biotic (Fauna) (Insects (Bee))

Plant Care and Propagation

Light Preference Full Sun
Water Preference Moderate Water
Rootzone Tolerance Moist Soils, Well-Drained Soils
Pest(s) Chewing Insects, Sucking Insects
Propagation Method Seed
Propagation Method Remarks Choy sum seed has no dormancy, but it is advisable to wait for at least for a week after seed drying before sowing. 
Seed / Spore Germination Duration 3 days to 5 days


Foliage Retention Evergreen
Mature Foliage Colour(s) Green
Foliar Type Simple / Unifoliate
Foliar Arrangement Along Stem Rosulate / Rosette
Foliar Attachment to Stem Petiolate

Floral (Angiosperm)

Flower Colour(s) Cream / Off-White, Yellow / Golden
Flower Grouping Cluster / Inflorescence
Flower Location Terminal
Inflorescence Type Raceme

Image Repository



Master ID 31551
Species ID 5950
Flora Disclaimer The information in this website has been compiled from reliable sources, such as reference works on medicinal plants. It is not a substitute for medical advice or treatment and NParks does not purport to provide any medical advice. Readers should always consult his/her physician before using or consuming a plant for medicinal purposes.
Species record last updated on: 25 January 2022.