Mustard family (Brassicaceae)
Description: This plant is a winter annual, spring annual, or biennial. It is initially a low-growing rosette with pinnatifid leaves up to 3" long. Later, the stems bolt upward, branching occasionally to frequently, and the plant becomes about ¾-1½' tall. When fully developed, it frequently has a bushy appearance, particularly in the absence of much competition. The cauline leaves are up to 3½" long and ¾" across, and usually oblanceolate or obovate. They are sessile at the base (appearing to have winged petioles), and the larger leaves have a few coarse teeth toward their tips. The stems are green or slightly reddish pink, and are covered with fine white hairs that are very short. The upper stems terminate in cylindrical racemes about 2-4" long that have small white flowers. Each flower has 4 white petals and 4 green sepals, and is less than 1/8" (3 mm.) across. A typical raceme will have a few flowers in bloom at the top, while below they have been replaced by seedpods about 1/8" (3 mm.) in length at varying stages of maturity. Each flattened seedpod has a round oval shape with a small notch at the tip. Various plants can be in bloom anytime from late spring to fall, peaking during early summer. The flowers have no noticeable scent. The individual seedpods can be carried a short distance by the wind, while on other occasions an entire raceme of mature seedpods will become detached from the mother plant and tumble away in the wind. The root system consists of a slender, branching taproot.
Cultivation: The preference is full or partial sun and moist to dry conditions. The soil can contain loam, gravel, or clay, and range from sterile to highly fertile. The lower leaves may turn yellow and wither away during a drought, but this is normal. This weedy plant reseeds itself readily and can spread to undesirable locations.
Range & Habitat: The native Common Peppergrass is very common and it occurs in every county of Illinois (see Distribution Map). This plant can be found occasionally in disturbed areas of prairies. However, it is more common in developed areas, including fields, pastures, vacant lots, roadsides and railroads, lawns and gardens, gravelly junkyards, and waste areas.
Faunal Associations: The tiny flowers appear to be visited primarily by Syrphid flies for nectar. Other occasional flower visitors include little carpenter bees (Ceratina spp.), Halictid bees, masked bees (Hylaeus spp.), Eumenine wasps, Tachinid flies, Anthomyiid flies, and others. However, Common Peppergrass is probably capable of self-pollination without the assistance of these insects. The caterpillars of a few species of butterflies and moths feed on the foliage and other parts of this plant, including Pieris rapae (Cabbage White), Pontia protodice (Checkered White), Eustixia pepula (Snout Moth), and Evergestis pallidota (Purple-Backed Cabbage Worm Moth). The peppery leaves are probably not favored by mammalian herbivores, although rabbits and groundhogs may consume small plants during the spring when little else is available.
Photographic Location: The photographs were taken on the grounds of the webmaster's apartment in Urbana, Illinois.
Comments: This is a native plant in a family that is dominated by introduced plants from Eurasia. The various members of the Mustard family are often difficult to distinguish from each other. One distinctive feature of this species is the rounded oval shape of the small flat seedpods, each with a tiny notch at the tip. The seedpods of similar species tend to be shaped somewhat differently, or have a larger size. Other kinds of mustards have long slender seedpods, called 'siliques,' with a very different appearance. The peppery young leaves of Common Peppergrass are edible, and they can be added to salads.