Momordica charantia is a tropical and subtropical vine of the family Cucurbitaceae, widely grown for edible fruit, which is among the most bitter of all vegetables. English names for the plant and its fruit include bitter melon or bitter gourd (translated from ), and karela from the Indian name of the vegetable.

The original home of the species is not known, other than that it is a native of the tropics. It is widely grown in South and Southeast Asia, China, Africa, and the Caribbean.

Description

The herbaceous, tendril-bearing vine grows to 5 m. It bears simple, alternate leaves 4-12 cm across, with 3-7 deeply separated lobes. Each plant bears separate yellow male and female flowers.

The fruit has a distinct warty looking exterior and an oblong shape. It is hollow in cross-section, with a relatively thin layer of flesh surrounding a central seed cavity filled with large flat seeds and pith. Seeds and pith appear white in unripe fruits, ripening to red; they are not intensely bitter and can be removed before cooking. However, the pith will become sweet when the fruit is fully ripe, and the pith's color will turn red. The pith can be eaten uncooked in this state, but the flesh of the melon will be far too tough to be eaten anymore. Red and sweet bitter melon pith is a popular ingredient in some special southeast Asian style salad. The flesh is crunchy and watery in texture, similar to cucumber, chayote or green bell pepper. The skin is tender and edible. The fruit is most often eaten green. Although it can also be eaten when it has started to ripen and turn yellowish, it becomes more bitter as it ripens. The fully ripe fruit turns orange and mushy, is too bitter to eat, and splits into segments which curl back dramatically to expose seeds covered in bright red pulp.

Bitter melon comes in a variety of shapes and sizes. The typical Chinese phenotype is 20 to 30 cm long, oblong with bluntly tapering ends and pale green in color, with a gently undulating, warty surface. The bitter melon more typical of India has a narrower shape with pointed ends, and a surface covered with jagged, triangular "teeth" and ridges. Coloration is green or white. Between these two extremes are any number of intermediate forms. Some bear miniature fruit of only 6 - 10 cm in length, which may be served individually as stuffed vegetables. These miniature fruit are popular in Southeast Asia as well as India.

Culinary uses

Bitter melons are seldom mixed with other vegetables due to the strong bitter taste, although this can be moderated to some extent by salting and then washing the cut melon before use.