Tag Archives: crucifer

Botany lab of the month: Contrasting brassica plants in the garden

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This is just a quick post about some instructive cruciferous vegetable (family Brassicaceae) anatomy and within-species diversity apparent in my garden at the moment.

Red Russian kale, rutabagas, and canola oil are all different varieties of Brassica napus. Red Russian kale and rutabagas are in my garden now, and the amplification of leaves and roots, respectively, through domestication is evident.

Red Russian kale (Brassica napus)

The rutabaga leaves are large, lobed, and somewhat grayish, like the Russian kale, but they are tougher and not as numerous as on the kale.

rutabaga plant (Brassica napus; Brassicaceae)

You’ll just have to take my word for it that there is no giant rutabaga-like root (technically a swollen hypocotyl, the fused lower stem and taproot, like a turnip, radish, or maca) straining the soil surface on the kale plant.

rutabaga

Anatomical differences amplified through domestication on otherwise vaguely similar-looking cruciferous vegetable plants is also visible on Brussels sprouts and collard greens, two different varieties of Brassica oleracea. A farmer or gardener familiar with the gestalt of the plants will easily identify a Brussels sprouts plant from afar as distinct from a collard greens plant, although the large plant and leaf size are similar.

Brussels sprouts plant (Brassica oleracea)

collard greens plant (Brassica oleracea)

Up close, though, you’ll see that the larger, more tender collard greens leaves have only a very tiny bud in their leaf axils (where the leaf joins with the stem).

Giant collard green leaves subtend very tiny axillary buds.

The developing Brussels sprouts, though, are not nearly done growing and are already much larger than the axillary buds  in any other variety of B. oleracea.

Young Brussels sprouts are really just giant axillary buds developing on the stalk.

While red Russian kale is Brassica napus, most of all the other kales are leafy varieties of Brassica oleracea, along with collard greens, Brussels sprouts, cabbage (which is the enlarged terminal bud, similar to the axillary bud), kohlrabi, broccoli, and cauliflower (read about this diversity and more about the anatomy involved in our essay The extraordinary diversity of Brassica oleracea). Last year we let one of the B. oleracea kales, a curly green winterbor variety, overwinter. Many of these brassicas retain the biennial life cylce of their weedy Mediterranean ancestor (read about it in our essay Caterpillars on my crucifers: friends or foes?), so overwintering is something for which a kale plant can prepare itself. The term biennial means that the plant’s life cycle requires two years to complete. In the first year the plant produces a profusion of leaves (the “rosette”). In the second year the plant flowers, sets seed, and dies. The leaves from the first year die over the winter. It is the job of those axillary buds to survive the winter as tightly wrapped bundles of overlapping leaves that will be familiar to Brussels sprouts fans. In the spring those leaves in the axillary buds unfurl and grow as the tiny stem that supports them elongates. This unfurling of leaves from otherwise small axillary buds was apparent this spring in our overwintering kale.

This winterbor kale stem overwintered. Above each leaf scar (from last year) new leaves are expanding on a new lateral stem from the axillary buds.

If you’d like to read even more about cruciferous vegetables in the mustard family (Brassicaceae), we have a few other longer essays that fill in some of this back story:

Thanksgiving turnips and the diversity of the genus Brassica

The most political vegetables: a whirlwind tour of the edible crucifersGreens: why we eat the leaves we do

Maca: A Valentine’s Day call for comparative biology

Alliums, Brimstone Tart, and the raison d’etre of spices

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If it smells like onion or garlic, it’s in the genus Allium, and it smells that way because of an ancient arms race. Those alliaceous aromas have a lot of sulfur in them, like their counterparts in the crucifers. You can combine them into a Brimstone Tart, if you can get past the tears.

The alliums

DSC09511

garlic curing

The genus Allium is one of the largest genera on the planet, boasting (probably) over 800 species (Friesen et al. 2006, Hirschegger et al. 2009, Mashayehki and Columbus 2014), with most species clustered around central Asia or western North America. Like all of the very speciose genera, Allium includes tremendous variation and internal evolutionary diversification within the genus, and 15 monophyletic (derived from a single common ancestor) subgenera within Allium are currently recognized (Friesen et al. 2006). Only a few have commonly cultivated (or wildharvested by me) species, however, shown on the phylogeny below. Continue reading →

The most political vegetables: A whirlwind tour of the edible crucifers

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arugula

Jeanne provides an overview of the cultivated brassicas.

Two days after the re-election of Barack Obama, the arugula at the farmer’s market reminded me of John Schwenkler’s excellent commentary from the 2008 campaign season on political trends in food choices, taking issue with Republican opposition to arugula. Arugula was the subject of a gaffe by then-candidate Obama.  Afterward the vegetable joined lattes in the pantheon of foodstuffs entirely in custody of liberals, according to some pundits on the political right.

broccoli

Arugula was not the only, or even the most recent, brassica (a species from the mustard family, Brassicaceae) to be dragged into the American political fray.  Marion Nestle has a great commentary on two memorable instances when broccoli entered national political discourse, first when George H. W. Bush disavowed the vegetable, and then recently when Antonin Scalia turned the vegetable into a symbol of government imperialism during the Supreme Court’s consideration of the Affordable Care Act.

cabbage

In July 1948 Truman called both houses of Congress back from recess for what is now known as the Turnip Day Session, starting on, as he said, “what we in Missouri call Turnip Day,” the 25th of July.  The designation comes from an old Missouri saying: “On the 25th of July, sow your turnips, wet or dry.”  During World War I sauerkraut in the United States for a time became “Liberty cabbage,” a marketing predecessor to the Freedom Fries in the George W. Bush-era congressional cafeteria.  The re-labeling came from American manufacturers of sauerkraut, the German name for the lacto-fermented salted cabbage popular in much of Europe and Asia, who worried that Americans would reject a product with a German name (incidentally, though smelly, making your own sauerkraut is easy and yields satisfying results).

watercress

The relative frequency of brassica appearances in political discourse reflects their abundance in the modern grocery cornucopia.  In previous posts we discussed the numerous varieties of Brassica oleracea (including kale, collard greens, Chinese broccoli, Brussels sprouts, kohlrabi, cabbage, broccoli, and cauliflower) and other Brassica species (turnips, rutabagas, rapini, napa cabbage, tatsoi, bok choy, mizuna, mustard greens, mustard seeds, mustard or canola oil).  This post completes our whirlwind tour of Brassicaceae food plant diversity. Continue reading →

The extraordinary diversity of Brassica oleracea

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Before the caterpillars attacked: Red Russian kale seedlings

Jeanne turns her frustration with caterpillars in her garden into an exploration of the botany behind an extraordinary species:  Brassica oleracea.

White cabbage butterflies (Lepidoptera: Pieris rapae) decimated the fall kale crop in our garden.  To be fair, the abundant green caterpillars did not consume the entire blade of every leaf.  The remaining nibbled leaves, however, in my husband’s view, no longer resembled food so much as a caterpillar farm that would be tedious to turn into food.  He ripped out the caterpillar farm, threw it on the compost bin, and replaced it with lettuce.  Unlike kale, which is in the mustard family (Brassicaceae), lettuce is in the sunflower family (Asteraceae) and is therefore not even remotely attractive to white cabbage butterflies.

Caterpillar damage on young green curly kale in the garden at Monticello

I was tempted to save the hole-riddled leaves from their compost fate, in part because I know that the munching of the caterpillars actually increased the foliar concentration of some of the compounds that contribute to kale’s nutritious reputation, and also because plummeting autumn temperatures impart an extraordinary sweetness to kale and the other cruciferous vegetables that are all actually varieties of the same species, Brassica oleracea: cauliflower, cabbage, kohlrabi, Brussels sprouts, Chinese broccoli, and collard greens.  The details of the chemical consequences of caterpillar consumption will soon get a post all their own.  This post is dedicated to the botany and evolutionary biology behind the amazing diversity of B. oleracea. Continue reading →