I first came across a medicinal plant that is called ‘ulam raja’ when I was doing a research project on plant antioxidants during my Food Science and Technology undergraduate days in the National University of Singapore. Thanks for my Malay friend, Hidayat, he was the one who brought me to Geylang Serai wet market on several Sunday mornings to search for vegetables and plants that are consumed by the local Malay community. I have not seen it being put up for sale in most other markets. In the local market, bundles of fresh, young and tender tips of this plant are put on sale. They wilt quickly, however, under our hot weather here.
Botanically known as Cosmos caudatus, it is sometimes called ‘wild cosmos’ by locals here but it is mostly refered to via its Malay name, ulam raja, which translates into ‘king vegetable’. Native to tropical America, it was first introduced to Philippines via the Spaniards, according to Plant Resources of South East Asia (PROSEA). The pinnate to pinnatipartite leaves of this plant are consumed as a leafy vegetable, usually in the raw form, but sometimes also cooked and mixed with coconut sauce and chillies. It constitutes as one of the more common raw plant leaves eaten a salad-like form, called ‘ulam’ by the local Malay community as well as those in Indonesia and Malaysia.
For the uninitiated, the leaves of ulam raja tastes raw and somewhat astringent. When crushed, the leaves emit an odour that is reminiscent of mango. It is considered as a medicinal herb which is believed to possess the ability to cleanse the blood and strengthen bones due to its high calcium content. From my research, a preliminary one which was done with my then postgraduate colleague, the dried leaves of this plants contain high amounts of potent antioxidants. The results of our work was published in the following paper:
Shui G, Leong LP, Wong SP. (2005) Rapid screening and characterisation of antioxidants of Cosmos caudatus using liquid chromatography coupled with mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci. 827(1):127-38.
The plant itself can grow quite tall, up to 3 m tall but is an annual or a short-lived perennial herb. It produces dainty, attractive pink flowers when mature. It should not be confused with the yellow- and orange-flowered Cosmos sulphureus as both species are similar vegetatively and have some vernacular names (randa midang in West Java) in common. The latter are more important as ornamental plants that are a common feature during Chinese New Year.
The ulam raja plant was once difficult to find in Singapore. It can sometimes be found naturalised in abandoned kampongs or wastelands. Occasionally, one is able to find a colony being grown by a Malay resident in a community garden. A few years ago, it was almost impossible to buy pots of this plant. Only recently, I discovered World Farm, a Singaporean wholesale nursery stocking some pots of it for sale to the public. I managed to get some young plants that were weeded out from a colleague’s park a couple of months ago.
This plant is rather easy to grow. It thrives in a sunny spot outdoors with well draining, fertile and moist soil. It is a big drinker and demands a constant supply of food. Under optimal conditions, it grows quickly, flowers and sets seeds very readily. Plants self seed easily and can quickly become a weed in a garden. Harvesting of leaves can commence once plants are 6 weeks old and subsequent ones can be done every 3 weeks. Regular harvesting will stimulate the production of useful and edible foliage and helps to delay flowering.