This introduced annual wildflower is 2-8" tall. It often branches near the base, but its stems are unbranched above. The slender stems are light green and hairy. The lower leaves are up to 3/8" long and across; they are yellowish green to green, hairy, oval-orbicular, crenate along their margins, and opposite. The petioles of the lower leaves are very short (about 1/8" long). As a plant matures, there is a tendency for the lower leaves to turn brown and wither away. The middle to upper leaves, where the flowers develop, are up to ¼" long, linear-oblong to lanceolate in shape, smooth or slightly crenate along their margins, sessile or nearly so, and alternate. Like the lower leaves, they are yellowish green to green and hairy. Solitary flowers develop from the axils of the middle to upper alternate leaves. Each flower is 1/8" across, consisting of a blue-violet to blue corolla with 4 petal-like lobes, 4 hairy green sepals, 2 stamens with white anthers, and a pistil with a single style. The corolla usually has a few faint veins originating from the center of the flower. The sepals are lanceolate-oblong and somewhat longer than the corolla. The tiny flowers bloom near the apex of the stems from mid-spring to mid-summer for 1-3 months. Each flower is replaced by an obcordate (heart-shaped) seed capsule. Individual seed capsules are 1/8" long, 1/8" across, somewhat flattened, and ciliate. Both the flowers and seed capsules are nearly sessile. Each seed capsule is 2-celled and contains many tiny seeds. The root system consists of a slender much-branched taproot. This wildflower reproduces by reseeding itself and it occasionally forms colonies.