Kadugu, rai in Hindi, is brown or Indian mustard, the small dark seed that pops in hot oil at the start of so many South Indian dishes. In North India the same plant is grown as a winter oilseed for kachi ghani mustard oil, and its leaves go into sarson ka saag. Rajasthan is the largest grower. Bengal grinds it into kasundi, a sharp mustard sauce. It arose as a natural cross between turnip, Brassica rapa, and black mustard.
- Botanical name
- Brassica juncea (L.) Czern.
- Family
- Brassicaceae
- Tamil
- Kadugu
- Hindi
- Rai
- Sanskrit
- Rājikā
- Parts used
- Seeds, Seed oil, Leaves (when grown as a green)
- Habit
- Annual brown mustard; seed is the tadka spice, leaf is a winter green
- Last updated
- 2026-10-30
How to recognise Kadugu
It is an upright annual, often waist- to shoulder-high, with bright green, often frilly leaves.
The upper leaves have short stalks and do not clasp the stem, unlike turnip and sarson.
Bright yellow, four-petalled flowers form long, loose sprays.
The pods are slender, spreading and beaked, with small round seeds.
The seeds are reddish-brown to dark brown, larger than black mustard seed.
Traditional use of Kadugu
Kitchen
Kadugu is fried in oil with curry leaves and urad dal as the tempering for sambar, poriyal and chutneys.
South Indian food practice
Kitchen
Cold-pressed kachi ghani mustard oil is the main cooking oil of Bengal, Bihar, Odisha and Punjab.
North and East Indian food practice
Kitchen
Ground mustard with green mango and salt is fermented into kasundi in Bengal.
Bengali food practice
Modern notes on Kadugu
Traditional Indian mustard oil is high in erucic acid, which is why some countries sell it labelled for external use only.
India approved environmental release of a genetically modified hybrid mustard, DMH-11, in 2022, a decision still contested in court.
The pungency comes from sinigrin, which breaks down into allyl isothiocyanate when crushed seed meets water.
Its leaves are rich in vitamin K, vitamin C and calcium.
Kadugu safety
Mustard is a common food allergen. Mustard oil should be bought from trusted sources, since adulteration with argemone oil has caused epidemic dropsy in India.
Ecology and sourcing
It probably arose in Central Asia or north-west India from a cross of turnip and black mustard.
Bees pollinate it, and mustard fields are important for honey production in North India.
Aphids are its main pest in winter fields.
Related plants
Also in Brassicaceae
Questions about Kadugu
Is kadugu the same as rai?
Yes. Both are brown mustard.
Why does mustard pop in oil?
Moisture inside the seed turns to steam and bursts the coat.
Is mustard oil safe to cook with?
It is a traditional cooking oil in India; some countries restrict it because of erucic acid.
What is kasundi?
A sharp, fermented mustard sauce from Bengal.
Is sarson ka saag made from Kadugu plant?
Often, along with Brassica rapa greens.
Sources
- Brassica juncea (L.) Czern. — Plants of the World Online, Kew (search) (accessed 2026)
- Wikidata item Q504781 (Brassica juncea)
Educational page about a plant. It is not medical advice, not a diagnosis, and not an offer to sell. Traditional use is historical. If you need care, ask a licensed clinician. Questions: hello@meevamed.com.