Yellow rocket is a mustard native to Eurasia that was introduced long ago and today is found across North America. It is a leafy, much-branched biennial plant, growing from a taproot, that can grow to 2 feet tall. The stems are hairless and ridged.
The flowers are many, crowded, bright yellow, with the typical mustard-family configuration of 4 petals in a crosslike formation, about ⅜ inch across.
Blooms April–June.
The leaves are alternate, usually hairless, pinnately lobed or pinnately compound; margins coarsely shallow-toothed, or entire. The outermost lobe of the leaf is oval, circular, or wedge-shaped and much larger than the sections below. The lower stem leaves are on long petioles (leaf stems); higher along the stem, the leaves are often sessile (stalkless). The leaves become smaller and smaller the higher they are on the stem.
The fruit is a long seedpod (technically, a silique); these form at the bottom of the cluster as new flowers open at the tips of the flower stalks.
Similar species: Missouri has many species in the mustard family. Yellow rocket is one of the most common; the yellow flowers, in the typical mustard-family configuration, and the shape of the stem leaves are distinctive.
Height: to 2 feet.
Statewide.
Habitat and Conservation
Occurs in cultivated and fallow fields and pastures, on stream banks, along roadsides and railroads, in waste places, and in a variety of open, disturbed areas.
This member of the mustard family is native of Europe and Asia. It is widely naturalized in North America. It has been here so long that there are historical records of Cherokees using it medicinally.
Status
Nonnative wildflower long established in North America.
Human Connections
The young leaves of yellow rocket have been eaten cooked or raw, although newer evidence indicates that chemicals in this plant can cause kidney trouble. Historically, it was used medicinally as a tea to treat a number of ailments.
The mustard family, which includes familiar garden plants such as broccoli, cabbage, and radishes, used to be called the Cruciferae because of the cross shape formed by the four petals.
Ecosystem Connections
Yellow rocket can cover large areas, especially in fallow fields, along roadsides, and other areas with disturbed soils. It does not seem to invade healthy native plant communities to a large extent.
A variety of insects, including ants, bees, and butterflies, harvest nectar and pollen from the flowers.
Several butterfly and moth species use plants in the mustard family as food plants, laying their eggs on the leaves, which the emerging caterpillars eat. Notable examples are the checkered white, falcate orangetip, and familiar but nonnative cabbage white.
A number of leaf beetles and other insects eat the foliage, too.
