Garden Plant Families – Brassicaceae

When identifying plants, people tend to know the names of the individual species. This is echinacea. This is lemon balm. This is a tomato. We rarely step back and ask, what do certain plants all have in common? But this information can be SUPER useful, both in areas such as plant identification, and for things like crop rotation from year to year. So, at long last (I’ve had this idea for years) I’m writing a series on culinary plant FAMILIES.

This series will ultimately include: the onion family (Amaryllidaceae – often called Alliums, and previously known as the lily family), beans and peas (Fabaceae – often called the legumes or pulses), mints (Lamiaceae – which includes MANY of our herbs), tomatoes and their kin (Solanaceae – often referred to as the nightshades), melons, cucumbers and squash (Cucurbitaceae – aka the cucurbits), the sunflower family (Asteraceae – what used to be called the composite or aster family), spinach and chard (Amaranthaceae – which also includes some edible weeds and grains), corn and other grains (Poaceae, or grasses), the carrot family (Apiaceae, also refered to as Umbelliferae or simply the parsley family, which includes may of our herbs), the rose family (Rosaceae, which includes may of our fruits and nuts including strawberries, almonds, apples and the stone fruits) and lastly, the mustards, which include things like broccoli, cabbage, and kale (Brassicaceae – which used to be called Cruciferae, aka the cruciforms).

All those Latin names. Seems scary and intimidating, right?! But really, its not. It’s just unfamiliar. And by learning these families, not only will your garden improve, but your ability to identify plants in the wild will also vastly increase.

As a companion to this series, I highly recommend the brilliant book Botany in a Day. The Patterns Method of Plant Identification by Thomas J. Elpel. This book, written by a non botanist, brings the language and science of plant identification down to a layperson level, and because Elpel is also an herbalist and forager, edibility and medicinal use of many plants is also mentioned. Most plant families are covered in a one or two page spread, making the learning quick and accessible.

The seed pods in this family are also distinct. Called a silique (drawing above) or silicle (drawing below), when ripe, the outside walls of the seed pod fall away leaving the translucent interior portion holding the seed intact. Pods always spiral up the stem a bit like a staircase. Seeds themselves are small and round and, well, look just like a mustard seed. This year I managed to get some of mine mixed up, and had two broccoli and a kale in the kohlrabi bed and a collard green in with the Chinese broccoli, because you can NOT tell them apart when the plants are small.

Domesticated mustards include horseradish (which can ONLY be propagated from root cuttings), water cress, radish, turnips & rutabaga, mustard greens, arugula, culinary mustard seed, rapeseed (from which canola oil is made), broccoli, cauliflower, cabbage, Brussels sprouts, kohlrabi, kale and collard greens (which are actually ALL the same genus/species, Brassica oleracea, that have been selected for different character traits). Beloved garden companion and pollinator favorite alyssum is also in the mustard family.

Mustards tend to be early cool season crops, easily germinating in cool spring soils, able to withstand a frost, and quickly bolting and going to seed as the weather warms up. I plant mine at the same time I start my tomatoes, about March 15th, and then transplant out about a month later (slugs do a ton of damage to the young stems if I try to start directly from seed in the garden). I find our spring is too short to successfully grow cauliflower (we just get too hot too fast for the heads to form well), so I’m trying to grow it as a fall crop this year instead.

I keep my mustard family plants together in the garden, and rotate them to a new location each year. Larger plants tend do need a LOT of nutrition to pull off all of that growth, so plan on adding extra compost to that area in the spring and keep them well watered as our days heat up.

Garden pests include aphids (I can keep ahead of them with an organic spray in the spring, they tend to die off through the summer, and by fall, when they return, I’m SO over that crop anyway that I don’t really care) and cabbage moth caterpillars, easily controlled by a spray of organic Bacillus thuringiensis (called BT for short), which stops the caterpillars from feeding but is harmless to other insects in the garden. Thankfully, other than slug damage, I’ve not had issues with cutworms or other insects or diseases on this crop. I did have to stop trying to grow Chinese cabbage, as it was such a slug attractant that the plants looked like someone had taken a shotgun to them.

Wild mustards also seem to love disturbed ground, and you’ll often see wild varieties blooming like a yellow, white or purple carpet along roadways in the early spring. Low growing blue mustard (Chorispora tenella) has always been a favorite of mine. Weeds of the West lists some 16 different varieties of “weedy” mustards, including one of our common tumbleweeds, (Sisymbrium altissimum). Some of these wild mustards are indeed edible, but this is beyond the scope of this post, and beyond my current botanical knowledge. Our sheep eat up anything we throw over the fence.

Some of your garden mustard crops, if left to go to seed, will reappear on their own the following spring. I’ve had arugula and radish and mustard greens pop up all over the garden from plants gone to seed the previous year. It always feels a bit like meeting an old friend after a long absence when you recognize them. Keep in mind that this family is an outcrosser, meaning it will cross with its cousins thanks to the help from the bees. So best to only let one of them go to seed at a time if you want to save seed for next year. And remember, you’ll have the best luck with open pollinated (ie not hybrid) varieties.

The distinctive “bite” of many plants in the mustard family is due to varying concentrations of sulfur glycosides. A little can be a pleasant spring tonic or a bitter contrast to other flavors. Too much can be quite irritating, capable of blistering the skin with prolonged contact (hello mustard plaster). Mustard plants tend to become more strongly flavored as they get larger and the weather gets warmer, which is why arugula is so nutty and mild in the spring but downright fiery late in the season.

Due to these glycosides, mustards have also taken on a new role in organic growing in the last few years. That of a biofimigant. Biofumigation is the suppression of soil born pests and diseases through the use of plants that produce inhibitory chemicals. In most cases these biofumigant plants are chopped and incorporated into the soil to release their inhibitory chemicals. Mustard’s biofumigant properties have been successfully used for a number of years, particularly in potato cropland. (Google “mustard biofumigant” for more details).

I’ve never tried using them as a fumigant, but I do know that the timing of incorporating them into the soil is important. I did just recently learn that I have a Rhizoctonia and Fusarium fungus in my soil, which is why I have such a hard time growing peas and garbanzos in the spring. I may try planting garbanzos intermixed with culinary mustard (the stuff you can buy in bulk at the grocery store WILL germinate) next spring, just to see if it helps.

So, there you have it. The first in a series on garden plant families. Enjoy this large plant family, look for it when you’re out on a walk or a hike, and plant it early next spring for a tasty healthy versatile pantry staple.

© 2020 Miles Away Farm, where we managed to make it out of college without ever taking a plant systematics class (ie learning how to key out plants to genus/species), but continue to learn more every day.