Nepeta cataria, commonly known as Catnip, is a perennial herb belonging to the Lamiaceae family, also called the mint family. Native to Europe and Asia, this aromatic species is now widely naturalized across North America. Identifying its visual characteristics helps confirm the presence of nepetalactone, the compound responsible for its famous effect on felines.
General Growth Habit and Overall Dimensions
Catnip is a herbaceous perennial that typically exhibits a bushy, somewhat rangy appearance. The plant usually reaches a height between one and three feet tall, and can spread to a similar width. Older plants tend to become mound-shaped with numerous branches.
A distinct feature for identifying Catnip, and all members of the mint family, is the square cross-section of its stems. The stems are often a light green or slightly gray color and are covered with fine, soft hairs, giving them a downy texture.
Distinctive Features of the Foliage
The leaves of Nepeta cataria are arranged in opposite pairs along the square stems. They are typically triangular-ovate or heart-shaped (cordate) with pointed tips.
The edges of the leaves are coarsely toothed (serrated or crenate margins). Both the upper and lower leaf surfaces are covered in a dense layer of fine, soft hairs, resulting in a pale, grayish-green color. This covering gives the foliage a velvety texture and often makes the underside appear whitish or silvery-gray.
The leaves are attached to the stem by short petioles and can reach a length of up to three inches. When crushed, the foliage releases characteristic aromatic oils, which include the feline-attracting compound nepetalactone.
Appearance of Flowers and Bloom Structure
The small flowers are arranged in dense clusters called whorls, which are tightly packed into elongated, spike-like terminal racemes at the ends of the stems. Flowering occurs from late spring through the fall, typically blooming for a month or two at a time.
Each individual flower is small, tubular, and features a two-lipped (bilabiate) structure, typical for the Lamiaceae family. The corolla is usually white or a very pale lavender color. The lower lip often features small purple or pink speckles.
These flowers are highly attractive to various pollinators, including bees, wasps, and butterflies. After flowering, the plant produces small, three-sided nutlets, each containing up to four seeds, allowing the plant to self-seed readily.
How Catnip Differs from Common Look-Alikes
Gardeners often confuse Nepeta cataria (Catnip) with other ornamental Nepeta species, collectively called Catmint. Both are in the same genus and mint family, but they have distinct differences in appearance and growth. Catnip generally has a taller, more upright, and somewhat “weedier” growth habit.
Ornamental Catmint varieties are typically lower-growing with a more compact, mounding form. Catnip is distinguished by its fuzzy, grayish-green foliage and predominantly white or pale pink flowers. Catmint usually has smaller, darker green leaves and produces denser, more showy flowers that are typically deep lavender or blue.
Catnip tends to flower once or twice in the season, while many Catmint cultivars are bred to flower almost continuously. Nepeta cataria contains a high concentration of nepetalactone, whereas ornamental catmints contain much lower concentrations of the compound.