Pennycress

Pennycress is a common name that can refer to several species of plants, most notably those in the genus Thlaspi, which are members of the Brassicaceae family. These plants are typically annuals or biennials characterized by their small, often circular or ovate seed pods, which resemble old English pennies, giving them their name. The leaves are often basal, forming a rosette, and can be toothed or lobed. Flowers are usually small and white or pink, appearing in spring or early summer.

Species commonly known as pennycress are found in temperate regions across the globe, often growing in disturbed soils, fields, and along roadsides. They are generally considered weeds, though some species may have historical uses or ornamental value. One species, Thlaspi arvense, also known as field pennycress or mithridate mustard, is widespread and known for its pungent odor and bitter taste.

Some research has explored the potential of certain pennycress species, particularly those within the genus *Noccaea* (formerly part of *Thlaspi*), for their ability to absorb heavy metals from contaminated soil, a process known as phytoremediation. The seeds of some pennycress varieties can also be a source of oil, and there has been interest in developing them as a biofuel crop. However, their weedy nature and potential for invasiveness are important considerations.