Lemongrass (Cymbopogon citratus) is a tall, clumping tropical grass whose pale, bulbous stalks carry an intense, clean lemon scent — bright and zesty like lemon peel but without any of the sour bite of the fruit. Native to maritime Southeast Asia and grown across the wet tropics, it is the citrus heart of Thai and Vietnamese cooking: the lemony lift in tom yum and tom kha, in green and red curry pastes, and in the marinades and grills of the wider region. Only the tender, paler base is eaten — bruised whole to perfume a broth, or finely sliced and pounded to a paste — because the long blue-green blades and the fibrous outer layers are too tough to chew.