Pennycress (Thlaspi arvense L.) is an introduced native of the Mediterranean region of Europe and Asia first reported in the USA as early as 1701. This long history explains the plant’s wide range throughout North America extending from Canada to Mexico as well as production agriculture’s adaptation to its presence. With its widespread distribution and long history, it is not considered an invasive or difficult weed species by farmers today.
As non-food member of the mustard family (Brassicaceae), Pennycress has very small (1mm in length, 400,000 per pound) seeds and grows as a winter annual. It produces a low-growing rosette in the fall after germination and this form protects the over-wintering plant from low temperatures and drying winds. The hearty plant is capable of being an effective ground cover protecting soil from the erosion forces of wind and water.
In the spring Pennycress resumes growing, flowers and becomes a prolific seed producer with yields as high as 20,000 seeds per plant and more than one ton per acre. The reported average date for mature seeds is between May 7 and May 23. This allows for an early June harvest and is early enough for full season soybeans to be planted with expectations of good yields. Growing it before soybeans allows for a later Pennycress harvest because soybeans can be planted later than corn.