Citronella is a tropical grass widely recognized for the distinct citrus-like oil extracted from its leaves. Belonging to the Cymbopogon genus, the two primary species are Cymbopogon nardus (Ceylon citronella) and Cymbopogon winterianus (Java citronella). Identifying the true grass species is essential to distinguish it from similar-smelling, non-related plants.
Overall Growth Habit and Dimensions
True citronella is a perennial, coarse, ornamental grass that forms dense, thick clumps over time. It grows from a stout, rhizomatous root structure, which allows the plant to spread slowly. This clumping habit gives the plant a bushy appearance at the base.
The plant typically grows between five and six feet tall when mature, though some varieties may reach up to eight feet in height. When cultivated, the plant is often propagated through the division of mature clumps, or rhizomes, rather than by seed. It thrives best in warm, humid, frost-free climates and is often grown as an annual in cooler regions.
Detailed Features of Leaves and Stems
The leaves are the most prominent feature and are characteristic of the Poaceae (grass) family. They are long, flat, and blade-like, growing up to three feet in length and about an inch wide. The leaves are medium to bright green and tend to droop gracefully at the tips.
A key identifying detail is the reddish or purplish coloration often found at the pseudostem, the tightly wrapped base of the leaf where it meets the ground. This reddish tint helps distinguish citronella grass from other closely related, all-green Cymbopogon species, such as culinary lemongrass. The leaf edges are noticeably rough (scabrid), though the surface itself is generally smooth.
The defining characteristic is the strong citrus scent that is released when the leaves are crushed or bruised. This aroma comes from the volatile essential oils, predominantly citronellal, citronellol, and geraniol, concentrated within the leaf tissue. Crushing the leaves breaks the oil glands, making the signature citronella fragrance immediately apparent and confirming the plant’s identity.
Identifying True Citronella Versus Common Imposters
Many people confuse true Citronella Grass (Cymbopogon species) with the plant commonly marketed as the “Citronella Geranium” or “Mosquito Plant.” This imposter is actually Pelargonium citrosum, a scented geranium belonging to an entirely different plant family. Visually, the two plants are drastically different, providing a clear method of identification.
True citronella is a tall, thin-bladed grass that forms an upright, fountain-like clump. In contrast, Pelargonium citrosum is a shorter, bushy subshrub with broad, deeply-lobed, fuzzy leaves. The geranium may also produce pinkish or pale purple flowers, a feature not seen on the true grass, which has small, insignificant flower clusters.
Although the scented geranium emits a lemony scent when disturbed, it does not contain the same oil concentration as the Cymbopogon grass. The true citronella grass is the commercial source for the insect-repelling oil. Knowing the difference between the tall, thin grass blades and the bushy, broad-leaved geranium is essential for correct identification.