Monkfruit, Siraitia grosvenorii , in Chinese 罗汉果 / 羅漢果 (Mandarin: luó hàn guǒ; Cantonese: lo4 hon3 gwo2), is said to be 300* times sweeter than sugar and is used industrially in making "artificial" sweeteners.
Lakantol monkfruit sweetener. Note: desite saying "No Additives" it does contain erythritol, another sweetener which has been linked to increased risk of heart disease.
Round these parts, the fruits are usualy sold dried and used in Traditional Chinese medicine (TCM) to treat cold symptoms and sore throats, by being used to make a kind of herbal tea or soup.
Dried Monkfruit
However, we do sometimes get them fresh when they are in season, which is now.
I have to say, I don't really like them. Too sweet with a bitter aftertaste. So far as I can see, most poeple just dry them themselves anyway!
The fresh ones are another thing I've never seen in supermarkets or even markets, but usually being sold by street vendors. Must ask why.
* Edited to add this is coincidentally the 300th post in this topic. Just noticed.