Siraitia grosvenorii is an herbaceous perennial vine of the Cucurbitaceae (gourd) family, native to southern China and northern Thailand. The plant is cultivated for its fruit, whose extract is nearly 300 times sweeter than sugar and has been used in China as a natural low-calorie sweetener for cooling drinks, and in traditional Chinese medicine to treat diabetes and obesity. It is harvested in the form of a round, green fruit, which becomes brown on drying. It is rarely used in its fresh form, as it is hard to store.

The monk fruit is notable for its sweetness, which can be concentrated from its juice. The fruit contains 25 to 38% of various carbohydrates, mainly fructose and glucose. The sweetness of the fruit is increased by the mogrosides, a group of triterpene glycosides (saponins). The five different mogrosides are numbered from I to V; the main component is mogroside V, which is also known as esgoside. The fruit also contains vitamin C.