Siraitia grosvenorii is a 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.

The plant"s fruit is often called in English language publications luo han guoor lo han kuo (from the Chinese luóhàn guǒ, 罗汉果/ 羅漢果). It may also be called la han qua (from Vietnamese la hán quả), arhat fruit, Buddha fruit, monk fruit, or longevity fruit (although this name has been used for several other fruits).

The scientific species name honors Gilbert Grosvenor who as president of the National Geographic Society helped to fund an expedition in the 1930s to find the living plant where it was being cultivated.

The vine attains a length of 3 to 5 m, climbing over other plants by means of tendrils which twine around anything they touch. The narrow, heart-shaped leaves are 10–20 cm long. The fruit is round, 5–7 cm in diameter, smooth, yellow-brownish or green-brownish in colour, containing striations from the fruit stem end of the furrows with a hard but thin skin covered by fine hairs. The inside of the fruit contains an edible pulp, which, when dried, forms a thin, light brown, brittle shell about 1 mm in thickness. The seeds are elongated and almost spherical.

The fruit is sometimes mistaken for the unrelated purple mangosteen.

The interior fruit is eaten fresh, and the bitter rind is used to make tea.

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.

Germination of seeds is slow and may take several months. It is grown primarily in the far southern Chinese province of Guangxi (mostly in the mountains near Guilin), as well as in Guangdong, Guizhou, Hunan, and Jiangxi provinces. These mountains lend the plants shade and often are surrounded by mists which protect the plants from the sun. Nonetheless, the climate in this southern province is warm. The plant is rarely found in the wild, so it has been cultivated for hundreds of years.