Pennycress, specifically Field Pennycress ( Thlaspi arvense ), is a widely distributed wild plant recognized for its edibility. This common annual, a member of the mustard family (Brassicaceae), has a long history of use in various cultures. Native to Eurasia, it has naturalized across North America and other temperate regions. While often considered a weed, this unassuming plant offers nutritional benefits and culinary applications.
Identifying Pennycress
Field Pennycress typically grows as a cool-season annual, reaching heights of 12 to 24 inches. It begins with a basal rosette of leaves in the fall or spring. These basal leaves are oblong or narrowly obovate, often with slightly wavy margins.
As the plant matures, it sends up an erect, ribbed flowering stalk. The stem leaves are alternate, stalkless, and clasp the stem with ear-like lobes at their base.
Flowers are small, white, with four petals, a characteristic feature of the mustard family. They bloom in dense clusters at the top of the stem, primarily from late spring through mid-summer.
One of the most distinctive features for identification is the seed pods. These are flat, round, winged, and measure about 1/4 to 1/2 inch in diameter, resembling miniature silver dollars with a distinct notch at the tip. When crushed, all parts of the plant may emit a strong, garlicky cabbage-like odor.
Edible Parts and Nutritional Aspects
The young leaves, seeds, and flowers of pennycress are edible. Young leaves and shoots are best harvested in early spring or fall, before the plant begins to flower, as older leaves can become bitter and pungent. These young leaves offer a mustardy, peppery kick and can be eaten raw or cooked.
Pennycress leaves are rich in protein. The seeds contain oil and can be ground into a powder. The plant provides general vitamins and minerals.
Foraging and Culinary Uses
When foraging for pennycress, select healthy plants from clean environments. Avoid areas prone to pollution, such as roadsides, industrial zones, or chemically treated lawns. The plant thrives in disturbed soils, gardens, and pastures; these are common foraging locations. Harvest young leaves by pinching them off at the base of the plant.
Young pennycress leaves can be incorporated into salads to add a peppery, mustard-like flavor. They can also be cooked as a potherb, sautéed with other greens, or used in soups and casseroles. If the leaves are too bitter, parboiling them in one or two changes of water can help reduce the strong taste.
The young, tender seedpods can be eaten raw, similar to radish pods. Mature seeds, which have a fingerprint-like pattern, can be ground and used as a mustard substitute or sprouted and added to salads. The flowers can serve as an attractive garnish for salads, adding a mild spicy note.
Important Safety Considerations
Accurate identification is essential when foraging for pennycress to avoid confusion with potentially harmful look-alikes, as mistaken identity is a primary safety concern. Always be certain of the plant’s identity before consumption.
Harvesting locations significantly impact safety. Plants growing in contaminated areas, such as near busy roadsides, agricultural fields treated with pesticides, or industrial runoff zones, may absorb pollutants like heavy metals or agricultural chemicals, making them unsafe to eat. Additionally, some individuals may have sensitivities or allergies to plants in the mustard family. Starting with small amounts when first trying pennycress is a good practice to assess individual tolerance. It is also important to note that the plant contains glucosinolates, which can be toxic to animals in large quantities.