Broccoli and cabbage, mustard and turnips. Radishes, Brussels sprouts, and cauliflower. Kale and kohlrabi. Asian vegetables such as daikon radishes, bok choy, and gai lan (Chinese broccoli). Never has a plant family had so many tasty members.
Then there are the beautiful relatives—cultivated basket-of-gold, candytuft, Persian cress and rock cress, for instance…
and wildflowers such as wallflower, desert plume (Stanleya pinnata), and various mustards.
Of course, every family has its black sheep. Shepherd’s purse is a European invader now established across the North American continent. It’s a nuisance in the garden, but happily is easy to pull out. Dyer’s woad, garlic mustard, dame’s rocket, and whitetop (aka hoary cress) are some of the more stubborn thugs; their invasive tendencies have landed them on the Colorado noxious weed list.
Brassicaceae, aka Cruciferae, is commonly called the mustard, or crucifer, family. It includes over 4,000 species in 372 genera, which are found on every continent except Antarctica. It’s not hard to identify them, as they are defined by a set of easy-to-recognize characteristics.
If you are a botanist, you may describe mustards as having “simple, although sometimes deeply incised, alternatingly set leaves without stipules or in leaf rosettes, with terminal inflorescences without bracts, containing flowers with four free sepals, four free alternating petals, two short and four longer free stamens, and a fruit with seeds in rows, divided by a thin wall (or septum).”[i] If not, keep reading….
I like to start with the flowers. They have four sepals and four petals. Looking at these photos explains why they’re called crucifers—the petals are in the shape of a cross (or perhaps an H). If you look closely, you can find four long stamens plus two more short stamens.
Once the flowers go to seed, the seeds are arranged in long pod-shaped capsules called silques, or shorter, more rounded capsules called silicles. If you’ve ever had broccoli (left) or radishes bolt before you could eat them, you know what I’m talking about. If you open one of those pods, you can see that the two long rows of seeds are separated by a thin membrane.
Finally, the leaves are alternately arranged on the stems (e.g., they take turns on each side), or they may form a rosette.
Mustards may be annuals, biennials, or perennials. Most are smallish herbaceous plants, although a few are shrubs. While all family members are edible, some people can taste the bitter glucosinolate compounds that broccoli and other family members contain. If that’s you, you can explain that you’re not a picky eater, just genetically more sensitive!