Foraging Fun: Thlaspi arvense

17°C is a little bit on the warm side for the middle of April, but I am certainly not about to complain, especially after enduring my first winter here in southern Manitoba. The winters here are as real and as long as I would ideally like to subject myself to, considering I hail from Canada’s deep south where the last few winters have been more akin to Vancouver than is typical for southern Ontario. But at long last, with the onset of warm days and cool nights, the first fresh green leaves of the year are emerging.

Since about the middle of last week, the old elm trees high above my head which line many of the streets here in Winnipeg are in full blossom, their small petal-less flowers giving their interweaving canopies a hazy reddish hue as they sway in the warm breezes. Along with them some of most eager and entrepreneurial plants aren’t wasting any time, taking advantage of the cool temperatures, moist soil and lack of competition from others that are only just being to become active.

This includes a diverse ensemble of different edible and medicinal plants, many of which are members of the mustard family Brassicaceae. This family is absolutely enormous (containing at least 4,060 accepted species) and boasts quite a large portion of the vegetables that humanity consumes for both nourishment and healing. This botanical family includes some of out most beloved vegetable crops such as broccoli, cabbage, cauliflower, kale, Brussel sprouts, radishes, rutabagas and turnips.


The species Brassica oleracea, a native of southern and western Europe, has been cultivated by different societies throughout the region into a bewildering range of shapes, sizes and forms. Kale, cabbage, collards, Brussels sprouts, broccoli, cauliflower, kholrabi and kai-lan (a popular Chinese green) are all domesticated forms of B. oleracea. This perfectly illustrates the vast genetic potential that many plants have and what generations of selective breeding by humans across landscapes and cultures can create.

Often growing alongside and within our vegetable garden beds are many wild or undomesticated relatives of these mustard family crops that are just as nutritious, if not more so than our favorite vegetables. These wild plants have the added advantage of being more or less entirely self-sufficient, essentially requiring little to no interference on our part for them to flourish except for us to tolerate them growing alongside our intended crops.

This is certainly one of the most attractive proponents of foraging for wild edibles; that they only require you to learn what they look like and where they can be found. There’s no seeding, weeding or watering involved, only the pleasure of searching for them, the satisfaction of finding them and the thrill of transporting them home, preparing them and bringing them to the table.


As I have mentioned, there are way more species of edible mustards than I could ever hope cover in a single article whilst refraining from turning it into a novel, and you can bet that I will come back to many of these other species as I encounter them on future outings. For now, I am going to focus on one that is particularly abundant: the field pennycress, Thlaspi arvense.

Pennycress is a rather inconspicuous and unassuming plant, very easily overlooked amongst the surrounding greenery. In spring, it presents itself as a basal rosette of flat, blunt-tipped leaves that are are widest near the middle (or occasionally towards the end) with shallowly scalloped edges on a narrow petiole. The roots are white to buff-colored, numerous and fibrous. When bruised or torn, the leaves release a unique odor. The flavor is unique but has been compared to mild onion and mustard with a hint of bitterness characteristic of many fresh, healthy wild greens.

Towards the end of spring or early in the summer, this biennial plant begins to flower. The basal rosettes that can be seen on the ground (once the snow melts from over top of them) germinated in the late summer or autumn of the previous year and hunkered down to overwinter. These plants will grow for a few weeks, producing more foliage before finally putting all of their energy into generating a tall flowering spike, setting seed and then dying.


This is the point when you would ideally like to harvest your pennycress; when new leaves are produced in the spring when the weather is still cool but before the temperatures climb and the soil dries out in early summer, stimulating the plant to flower. “Cress” is a common name for many different mustard family plants, and the ‘penny’ part of the name refers to the seed capsules which are nearly circular and flat, resembling coins.

Once late spring or early summer rolls around, the foliage begins to take on an overwhelming bitterness that makes it no longer suitable once the flowering stalk begins to develop. This threshold is dependent on personal taste as well as to individual plants; some can have a few open flowers and still be palatable while others with only the hint of a stalk may already begin to taste unpleasant, so you’ll have to get to know how much it too much for you through experience.

T. arvense is often exceedingly abundant in the right environments; usually there are hundreds of individual plants in an area once you notice your first one. They are short lived and early succession species; thriving in open areas and under disturbed conditions. Garden beds, hedgerows, lawns, sandy or gravelly hillsides, embankments, recently tilled fields as well as compost and manure piles are all suitable habitats for pennycress but the list goes on and on.

The foliage (or indeed the whole crowns of the plant) can be eaten raw or cooked. I personally like them lightly blanched and served with salt, pepper, lemon juice and butter. This is an excellent way to get accustomed to how they taste on their own, but they can of course be incorporated into soups, stews, stir fries, casseroles, salads or just about any other culinary ensemble that includes greenery.

Having now been formally introduced to pennycress, I encourage you to get out there and seek out this plentiful and healthful green that you have more than likely weeded out of your garden bed without knowing that it too, like your intentionally cultivated foods, can be a seasonal delicacy just like any other.