The aromatic grass known as lemongrass, or Cymbopogon citratus, is a staple in kitchens and traditional medicine worldwide, prized for its bright, sweet citrus flavor. Its popularity often leads to confusion, as its visual similarity is especially pronounced because many look-alikes belong to the same Cymbopogon genus. Understanding the definitive physical and chemical signatures of true lemongrass is the first step in correctly distinguishing it from its common visual imposters, making misidentification a common problem for gardeners and consumers.
Identifying True Lemongrass
True culinary lemongrass has a distinct set of physical characteristics. The most defining feature is the pale, bulbous base, or pseudostem, of the stalk, which should be entirely green or pale yellowish-green in color. These stalks are thick and firm, providing the structural material used for flavoring in many Southeast Asian dishes. When mature, the plant forms dense, upright clumps, typically reaching a height of two to four feet, with arching, strap-like leaves that are narrow, usually measuring about a half-inch in width.
The most reliable confirmation of identity lies in its unique fragrance, which is released when a leaf or stalk is bruised. This scent is a sweet, bright, and pure lemon aroma, lacking sharp or medicinal undertones. The chemical compound responsible for this signature fragrance is citral, found in high concentrations within the plant’s essential oil. This high citral content gives true lemongrass its desirable culinary quality for use in curries, soups, and herbal teas.
Citronella Grass: The Closest Look-Alike
The plant most frequently mistaken for culinary lemongrass is Citronella Grass. Citronella grass is noticeably larger than true lemongrass, often growing taller and wider, reaching heights of up to six feet with broader leaf blades that can exceed an inch in width.
The most reliable visual trait for distinguishing citronella is the color of its base, which consistently displays a magenta or reddish-purple tinge, especially near the lower parts of the stalk and new growth. A crushed leaf of citronella reveals a scent that is lemony but much sharper and more pungent than that of C. citratus. This aroma is dominated by the chemical compounds citronellal and geraniol, rather than citral, which explains why citronella is primarily cultivated for its essential oil used in insect repellent products. Due to its different chemical composition, citronella grass lacks the subtle sweetness of the culinary species and should not be used as a substitute in food preparation.
Other Visually Similar Grasses
Other grasses share the tall, fountain-like, and clumping growth habit of lemongrass, though their aromatic profiles are entirely distinct. Palmarosa, or Cymbopogon martinii, is another member of the same genus and presents a visual challenge with its similar narrow, grassy leaves and tall stalks. However, the crushed leaves of Palmarosa produce a sweet, rosy, and herbaceous scent. This unique fragrance is primarily derived from the compound geraniol, which is also responsible for the characteristic scent of rose oil.
Another visually similar plant is Vetiver Grass, Chrysopogon zizanioides, that grows in dense, upright clumps up to eight feet tall. While its above-ground appearance can be confused with lemongrass, the plant’s value comes from its root system, which can extend over 10 feet deep. Unlike the other fragrant grasses, which store their aromatic oils in the leaves and stalks, Vetiver’s signature fragrance is contained entirely within its roots. This root oil is earthy, woody, and smoky, making it a key component in perfumery.