Thyme is a popular, low-growing herb belonging to the Lamiaceae family, commonly known as the mint family. The Thymus genus contains hundreds of species, all sharing a similar, distinctive physical presentation. Understanding the plant’s morphology, from its overall shape to the minute details of its leaves, aids in accurate identification.
Growth Habit and Structure
Most commonly grown thyme varieties, such as Thymus vulgaris, present as a small, woody sub-shrub with a compact, bushy appearance. The plant typically reaches a mature height between 6 and 12 inches, forming a dense mound that spreads outward. Its stems are a defining structural element, becoming semi-woody and slightly angled or square, particularly towards the base.
The stems branch profusely, contributing to the plant’s tight, matted texture. They retain their foliage throughout the year in many climates. In late spring to early summer, thyme produces small, clustered flowers, typically white, pink, or light purple. These blooms appear at the terminal ends of the stems, contrasting delicately with the evergreen foliage.
Defining Characteristics of the Foliage
The foliage is the most reliable feature for identifying thyme. Thyme leaves are notably tiny, often measuring less than a quarter-inch in length, giving the plant a fine, delicate texture. They are arranged in opposite pairs along the stem, which is a common trait of the mint family.
The leaves are generally linear to ovate in shape and are often dark grayish-green or medium green. The margins of the leaves may be slightly revolute, meaning they are rolled under toward the underside. The surface can vary from smooth to slightly fuzzy, but their small size and dense arrangement create the herb’s characteristic bushy look.
Common Visual Differences Among Thyme Types
While common thyme maintains an upright, shrubby form, the genus includes significant visual variations, notably between upright and creeping types. Upright varieties, such as Lemon Thyme or Common Thyme, stand taller and are generally easier to harvest due to their erect, woody stems.
Creeping varieties, such as Woolly Thyme or Mother-of-Thyme (Thymus serpyllum), exhibit a prostrate growth habit. They form dense, flat mats that hug the ground and rarely exceed a few inches in height. Their stems branch horizontally rather than vertically. The foliage of creeping types can also show distinct color differences, such as the silvery-gray, fuzzy leaves of Woolly Thyme or the slightly lighter green, sometimes yellowish tinge of Lemon Thyme.