Thyme-Leaved Speedwell
Veronica serpyllifolia
Figwort family (Scrophulariaceae)

Description: This perennial wildflower is 4-12" tall, producing several unbranched stems from its base. Individual stems are decumbent initially, but they become more erect when the flowers are produced. Each slender stem is light green, terete, and sparsely to moderately covered with fine appressed hairs. Pairs of opposite leaves occur along each stem. Early leaves have winged petioles, but later leaves are sessile. The blades of the leaves are -" long and about one-half as much across; they are medium green, elliptic-oblong to oval in shape, smooth or slightly crenate along their margins, and glabrous. Each upper stem terminates in a narrow raceme of flowers about 2-7" long. Individual flowers are produced in pairs or alternately along the raceme on short slender petioles up to " long. At the base of each flower, there is a leafy bract that is the same length or a little longer than the petiole; each bract is elliptic or oblong in shape, smooth along the margin, and glabrous.

Individual flowers are about " across, consisting of a short corolla with 4 rounded lobes, a short green calyx with 4 teeth, 2 stamens with white filaments and blue anthers, and a green ovary with a single style. The corolla is usually white (less often pale blue) with dark blue veins; the lowest lobe of the corolla is smaller in size than the lateral and upper lobes. The blooming period occurs primarily from mid-spring to early summer for about 2 months; some plants will bloom later than this if a disturbance damages their stems. The flowers are diurnal and lack significant fragrance. Each flower is replaced by a 2-celled seed capsule about " across that is obcordate and somewhat flattened. At maturity, each capsule splits open to release numerous tiny seeds. These seeds are small enough to be blown about by the wind. The root system is fibrous and rhizomatous. Colonies of plants are often produced at favorable sites.

Cultivation: The preference is full sun to light shade and moist to mesic conditions. Different kinds of soil are tolerated, including those that contain loam, clay, sand, or silt. Most growth and development occur during the cool rainy weather of spring.

Range & Habitat: Thyme-Leaved Speedwell is scattered across Illinois, although it is more common in the northern half of the state than the southern half (see Distribution Map). This non-native species was introduced into North America from Europe. Habitats consist of meadows, lawns, grassy areas of parks, and low areas along ponds, rivers, and springs. These habitats are usually disturbed and semi-shaded.

Faunal Associations: Very little is specifically known about floral-faunal relationship for this species. The flowers are cross-pollinated by flies and small bees (e.g., Syrphid flies, blow flies, and Halictid bees). These insect obtain primarily nectar from the flowers. In limited amounts, the foliage is not particularly toxic to vertebrate animals; it is probably eaten by the Cottontail Rabbit, Groundhog, and Canada Goose. The flat tiny seeds can cling to the feathers of birds, fur of mammals, and shoes of humans; this method of locomotion helps to spread the seeds into new areas.

Photographic Location: A lawn near Grand Rapids, Ohio.

Comments: This small wildflower is one of several weedy Veronica spp. that have been introduced from Europe. Because of its small stature, it is not often noticed except when sizeable colonies of flowering plants are in bloom. Such colonies can produce an attractive display in lawns as the flowers are usually held above the blades of grass. Thyme-Leaved Speedwell can be distinguished from other Veronica spp. by its terminal racemes of flowers; it does not produce axillary racemes of flowers, nor does it produce individual flowers from the axils of true leaves (as opposed to the smaller leafy bracts). The leaf blades of Thyme-Leaved Speedwell are less toothed than those of many introduced Veronica spp., and it is a smaller plant than most native Veronica spp. While the native Veronica peregrina (Purslane Speedwell) is no larger than Thyme-Leaved Speedwell, the former species has flowers that are more white and its stems are hairless.