Annual plant of southeast Asian origin with a tangy-flavored calyx used in drinks, sauces, or eaten fresh. The leaves are edible raw or cooked. Seeds are ground and used as a meal or as a coffee substitute in Africa. Prefers deep, fertile, well-drained loam. Fresh leaves contain 2-3% protein and traces of calcium, phosphorus, and iron. A short day plant that can be grown in temperate regions but will not produce fruit.