Lemongrass is an herb used in the kitchen for its citrus flavor and scent.Lemongrass is a tropical plant native to South and Southeast Asia, growing up to 3-8 feet tall, with a soft fountain of fragrant foliage. With a tangy lemony scent and flavor, lemongrass is widely used in Indian, Thai and Vietnamese cooking as well as medicine. It is also used to kill germs and as a mild astringent. … Lemongrass is also used in making vitamin A and natural citral.