This introduced perennial plant is usually 1' or less, branching frequently and forming a low-growing mat of stems and leaves across the ground. The 4-angled stems are prostrate to slightly ascending, and often form rootlets near the axils of the leaves when they touch the ground. The opposite leaves are about 1" long and across. They are green to purplish green, orbicular, and crenate along the margins. There is a flat indentation where the long petiole joins the base of a leaf. The pubescent upper surface has conspicuous palmate venation. Clusters of 1-3 tubular flowers develop from the leaf axils. These flowers are bluish violet to reddish purple and about ½" in length. The corolla of each flower is narrow at the base, but flares outward like a trumpet into spreading lobes. There is a notched upper lobe, a notched lower lobe, and 2 smaller side lobes. The lower lobe is larger than the others and functions as a landing pad for visiting insects. It has darker violet lines that function as nectar guides. Within the throat of the corolla, there are fuzzy hairs. Each flower has a single pistil with a divided style, 2 long stamens, and 2 short stamens. The pubescent calyx is about 1/3 the length of the tubular corolla, with 15 veins running along its length and 5 teeth along its outer edge. The blooming period usually occurs from mid-spring to early summer for about 2 months, although some plants may bloom later in the year if they remain in cool shade or a major disturbance prevents earlier bloom. Upon maturity, each flower is replaced by 4 dark brown nutlets. Each nutlet is ovoid, with 2 flat sides and an outer side that is rounded. The root system is fibrous and shallow. This plant often forms dense colonies by forming rootlets along the stems.