bitter gourd (or bitter cucumber) Momordica charantia, neither a true gourd nor a cucumber, although a member of the same cucurbit family as both. Another English name, balsam pear, is even less fitting. Names in India and the Philippines are, respectively, karela and ampalaya.
The plant is thought to be a native of India, but has been grown elsewhere for a long time and its use in SE Asia goes back a considerable way.
The knobbly fruit has a bitter taste, akin to that of a fresh, i.e. unpickled, gherkin. It is used as a vegetable in various tropical regions, including most SE Asian countries. It varies considerably in size (from 2.5 to 25 cm/1 to 10") and also in colour. Indonesians cultivate it as a garden vegetable and recognize numerous forms, including a large whitish one and smaller green ones.