Category Archives: Vegetables

The leftovers of 2020

Do you still have a bunch of celery leftover from Thanksgiving in the back of your fridge? With no holiday parties this year, you won’t be able to sneak it onto a holiday crudités platter. You could assemble silly little peanut butter and celery reindeer snacks, but that would just generate messier leftovers. Katherine tells you why you should put it all into a very elegant silky soup for the grownups.

Some of my happiest teaching days begin when I drag a rattling cartload of vegetables and razor blades over the paving stones and across the quad to my classroom. Then, for a couple of hours, edible roots and stems and leaves are handled, poked, hacked at, licked, bitten into, and passed between lab partners. Some of them become projectiles. Most become snacks right there. Potatoes fall into backpacks to be cooked later in the dorm. By the time we clean up, the scant inedible scraps fit into one small bag that I can tip inconspicuously into a campus compost bin.

It’s hard to imagine those days now. Before the pandemic, the only real potential hazards of these labs were food allergies and dissecting tool injuries. While I did provide hand wipes, nobody used them. Now after nine months of pandemic protocols, even just describing the labs triggers aversion.

Trying to teach botany during a pandemic is exactly why I ended up with leftover celery, and much too much of it. The week before Thanksgiving, Jeanne and I taught a virtual botany lab by video conference with some of the volunteers for the Friends of Edgewood Park. We imagined a plant-based Thanksgiving dinner and walked the volunteers through each of the main plant ingredients, while they dissected their own samples at home. The participants were good sports, and it was fun, even if nobody started a Brussels sprouts fight.

Celery (left) and fennel (right)

Celery (left) with close relative fennel (right)

After the event, it was a boon to have the remaining potatoes, sweet potatoes, herbs, leeks, oranges, green beans, and cranberries I had gathered for the demonstration. They were mostly still intact and free from community spittle, and I had plans for each of them. But then there were also those two imposing bundles of celery – stringy, strong tasting, and too long for the fridge. There was nobody I could send them home with. I certainly did not want to eat that much raw celery. Braising it à la Julia Child was no more appealing as I have always hated cooked celery.

Or so I thought. After consulting with Jeanne, a genius with umbel-bearing species, I improvised a basic celery and potato soup and added a little bit of the leftover rosemary. Slow cooking and a whirl in the blender transformed it into something silky and rich and delicious, without any of the strong overcooked green flavor I associate with celery chunks in soup. The recipe is below. But how did this simple treatment completely change the celery flavor?

base of a bunch of celery, showing leaf arrangement

Base of a bunch of celery, trimmed to show leaf arrangement

Fortunately for us all, the amazing Harold McGee has just published an instant classic, Nose Dive: a Field Guide to the World’s Smells. For his book, McGee has compiled table after table of the dominant smells (and their source molecules) for a wide array of vegetables and herbs, including celery. His painstaking work helped me understand why I should stop omitting this complicated species from my mirepoix.

From heavy scented to heaven scented

Raw celery has a fresh green scent to match its crisp texture, but it’s not bland, and it won’t hide behind the rest of the crudités on the platter. Its scientific name is Apium graveolens, and while the genus name has something to do with bees, the species name means “heavy-scented.” Its distinct celery smell comes largely from a volatile molecule called sedanenolide, which is a type of phthalide (McGee 2020). As assertive as it can be, this molecule affects our perception even at concentrations below what we can detect. One study found that a small amount of sedanenolide added to chicken broth raised all eleven measured positive flavor qualities relative to plain broth, as rated by a panel of tasters (Kurobayashi et al. 2008). So in addition to contributing a bit of its own flavor, the sedanenolide in celery boosts our sense that a dish is thick, savory, and complex.

Sedanenolide is not altered chemically by boiling, although it is volatile so some of it probably evaporates when celery is cooked. But cooking celery also transforms some of its chemical components to generate a completely different flavor arising from my new favorite molecule, sotolon.

Sotolon is described as tasting like fenugreek, which may not be helpful information if you have never tasted fenugreek by itself. Fenugreek seeds taste like maple syrup, but with a funky edge that veers into what some authors describe as “curry” at higher concentrations. It reminds me of the faint onion scent that lingers in the wood grain of a well used cutting board.

Fenugreek seeds. Click to enlarge.

Sotolon also contributes warm maple-like flavors to sherry and Madeira wines. I sometimes add it to oatmeal along with cinnamon, cloves, nutmeg, and ginger. You have to be careful with ground fenugreek, though, because the scent remains on your fingers all day, and you don’t want your oatmeal tasting faintly of onions. Reading about sotolon made me crave it, so I spiked some tea with fenugreek, and alongside the maple flavor, I caught occasional hints of celery seed in the steam.

Rosemary

Thanks to McGee’s masterful book, with an incredible index, I learned about some of my soup’s other scents as well. For example, cooked potatoes develop a nutty and earthy flavor because of pyrazines. Of course they also carry some sweetness from the carbohydrates stored in their flesh. Rosemary contains several interesting molecules that give it a resinous camphor scent, but in the soup, the rosemary notes mainly reflected its more woodsy compounds, borneol and peppery rotundone.

Borneol is a monoterpenoid that contributes to the scent of some pines and cypress, as well as ginger and citrus peels (McGee 2020). Rotundone is the sesquiterpenoid molecule that imparts a characteristic black-pepper aroma to Australian shiraz wines, and that’s where it was first discovered in 2008. It has since been identified in (of course) French syrah, some other wine varietals, black pepper, rosemary, basil, and even apple and mango (Geffroy et al. 2020). A substantial proportion of unlucky humans cannot smell rotundone at all. In one panel of French wine professionals and connoisseurs, 31% failed to detect it (Geffroy et al. 2017). Sadly, in COVID times we have all learned the term for this: anosmia.

With all that maple pepper woodsy pine aroma wafting from the bowl, no wonder my simple little three-plant soup turned out to taste like a walk in the woods on a sunny early winter’s day. Not bad for leftovers.

Portion of an advertisement from 1951 for Campbells soup

Portion of a 1952 advertisement from Better Homes and Gardens for Campbells soup. Click to enlarge.

Leftover celery and potato soup

  • Celery stalks (petioles, the part of the leaf below the flat compound blade)
  • Unpeeled chopped potatoes, at twice the volume of the celery. I used several small waxy types and a baking potato because they were left over from the virtual lab demonstration. The type may not matter that much
  • Several tablespoons of butter (1-2 tablespoons per bunch of celery)
  • Olive oil
  • Fresh sprig of rosemary, 2-3 inches long
  • Salt and pepper to taste

Chop celery petioles (“stalks”) and take note of their raw volume. Put the celery and the sprig of rosemary into a large stock pot and cook them slowly and gently in a generous dollop of butter, about one mounded tablespoon for each bunch of celery.

When the celery is very soft and translucent, but not brown, add chopped potatoes. The volume of potato  should be about twice that of the raw celery. Add a dash of olive oil and stir for a few minutes but do not brown the vegetables.

Add water to twice the depth of the vegetables and simmer until the potatoes are completely soft. Add salt and pepper.

Remove the rosemary sprig, but leave any leaves that have fallen off of the stem. Let the soup cool and purée it. Reheat to serve and add water to thin if necessary.

I was lucky enough to have some fresh goat cheese flavored with fennel pollen and black pepper from Pennyroyal Farm. I put a quenelle rustique (a plop) of cheese in the bottom of each bowl and poured the soup around it. Fennel is in the same family as celery, but its florets and pollen produce their own lovely set of volatile scents (Ferioli et al. 2017) that complement the celery without replicating it.

References

Ferioli, F., Giambanelli, E., & D’Antuono, L. F. (2017). Fennel (Foeniculum vulgare Mill. subsp. piperitum) florets, a traditional culinary spice in Italy: evaluation of phenolics and volatiles in local populations, and comparison with the composition of other plant parts. Journal of the Science of Food and Agriculture, 97(15), 5369-5380.

Geffroy, O, Descôtes, J., Serrano, E., Calzi, M.L., Dagan, L., & Schneider, R. (2018). Can a certain concentration of rotundone be undesirable in Duras red wine? A study to estimate a consumer rejection threshold for the pepper aroma compound. Australian Journal of Grape and Wine Research 24: 88-95.

Geffroy, O., Kleiber, D., & Jacques, A. (2020). May peppery wines be the spice of life? A review of research on the ‘pepper’aroma and the sesquiterpenoid rotundone. OENO One, 54(2), 245-262.

Kurobayashi, Y., Katsumi, Y., Fujita, A., Morimitsu, Y., & Kubota, K. (2008). Flavor enhancement of chicken broth from boiled celery constituents. Journal of Agricultural and Food Chemistry, 56(2), 512-516.

McGee, H. (2020). Nose dive: A field guide to the world’s smells. New York, NY: Penguin Press.

The Botanist Stuck in the Kitchen, rummaging for beets

Over these many weeks, humans have been forced into an uncomfortably close study of our own species’ behavior. Observations haltingly stream in through the internet and the TV, through hurried forays into the sparse public square, and through sometimes painful introspection. We are finding what we’ve always known, that humans are petty and petulant, compulsively social, and surprisingly sublime.

Meanwhile, without our clueless interference, non-human animals have gone about their business as normal. The male bi-colored redwing blackbirds where I live are putting on the biggest and flashiest red patches I’ve seen in years. Good luck, guys!

And the Canada geese, which normally annoy me with their poop and their nasty moods have become adorable as they sashay in pairs down the road towards their new nests on the empty golf course. In a few weeks they will be justifiably nasty again, hissing as they protect their babies from me, a silly runner, just trying to shed my own cranky mood into their territory.

Recently, after a run through a muddy patch of the trail stamped with goose footprints and lined with wild sea beets, I remembered that I had some old beets in the refrigerator. Time to do some botany!

For much more information about beets and their relatives, see our longer posts.

Botanizing in the kitchen with kale

The farmer’s market this weekend in late March of 2020 was disorienting, and not only because I was wearing a mask and gloves. It was hard to see which line of widely spaced people was snaking into which farmer’s stand, and many vendors had hung tarps and were helping customers through windows. But everyone was as community-spirited as usual, and many of us were uncharacteristically patient.

Yet again, I was beyond grateful for both the opportunity and the means to fill my fridge with fresh green vegetables, including kale. And I was way more excited than usual to find a bunch of kale that had started to elongate its stem and flower because I knew I could use it in another video in our special COVID-19 series of dispatches from our kitchens.

Here’s hoping you stay in good health and good spirits.

 

For many more details about Brassica oleracea see Jeanne’s many terrific posts from the past that cover B. oleracea diversity, chemistry, and comparative morphology.

The Botanist Stuck in the Kitchen, Saturday night artichoke edition

Welcome to another installment of our new special feature: a series of videos and posts that bring you into our kitchens as we join millions of people sheltering in place. So far, my local farmers market is open for business and local farmers are continuing to bring fresh food to our community, at some real risk to themselves. So so many of us are grateful.

I was lucky enough last week to pick up some gorgeous giant artichokes to prepare for Saturday night, which presented the opportunity for a virtual botany lab. Wherever you are sheltering, I hope that you are able to find some for yourself. Artichokes are full of antioxidants, specifically polyphenols, that have generally health-promoting effects. They are also rich in dietary fiber, which is a good thing if you have spent too much time on the sofa lately. And if you eat them with melted butter or olive oil, well, that can’t hurt your mood, now can it?

This video was only lightly edited and entirely unscripted, so please be patient with the pace and the occasional interruption by Caltrain.

For more details about artichokes, see my written explanation in an earlier post: How to make an artichoke: the facts about bracts, part 1

 

 

The Botanist Stuck in the Kitchen

It’s the spring of 2020, and like millions of others, we Botanists in the Kitchen are sheltering at home, trying to help flatten the curve. In other words, we are stuck in the kitchen. However, neither of us is complaining right now. Personally, I (Katherine) feel secure in my home, and I am (for now) healthy. I have access to fresh and nutritious food (thank you small-holder farmers), and at the end of the day I can go for a long run along a lovely creek lined with trees and birds. Both are opportunities to connect with plants, and this blog has always been about helping people connect to plants that might just be sitting in their refrigerators.

Like many other educators, I have also been preparing to teach a spring quarter botany course, from my sofa, through a laptop. In rethinking what is essential to the class and what might be necessary for my students in this moment, I decided to assign a new reading. It’s a 2015 study by some Stanford colleagues who found, basically, that a walk through a natural green space reduced anxiety compared to a similar walk through an urban area. Maybe that’s not surprising, but they also investigated potential mechanisms by measuring the way people’s brain activity differed in the two situations. Their data suggest that an immersive experience in “nature” (with plants) reduces the kind of unproductive rumination that feeds anxiety. Nobody has done the same experiment comparing our anxiety levels after scrolling through social media or after carefully preparing broccoli and marveling at the fractal arrangement of its unopened flower buds. I do have a prediction, though. Under the current conditions, maybe it’s time to move into the kitchen and see what’s in the fridge.

 

P.S. If you are food-secure and financially able at this time, please consider giving to your local food bank. Everyone should have nutritious fresh food for body and mind.

Reference

Bratman, G. N., Hamilton, J. P., Hahn, K. S., Daily, G. C., & Gross, J. J. (2015). Nature experience reduces rumination and subgenual prefrontal cortex activation. Proceedings of the national academy of sciences, 112(28), 8567-8572.

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

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

The Beet Goes On

In this Valentine’s Day edition, Katherine brings you a love song with a beet. Sweet and red, sort of heart-shaped, bearing rings, and definitely divisive – beets should be the unofficial vegetable of the holiday. And if you don’t feel like celebrating, then you can just sit alone and eat dirt.

Throughout two years of dating and our first six months of marriage, my husband and I had never discussed our feelings about beets. Then again, I had never made beets for him before. When I did, they were meant to bulk up a brimming vat of stew that would feed us every night for a week. In my husband’s version of the story, it lasted for three weeks. “I hope you like beets,” I announced that evening. “I may have added too many.”

Whether you love or hate beets, it is probably because they taste like dirt. Some people (my husband) can’t get over the flavor, and others can’t get enough of it. Some people experience beeturia, the appearance of bright red or hot pink urine after they eat red beets. Maybe this sight unsettles you. Or maybe you embrace the opportunity to track the transit of beet pigments through your body. You may admire their lovely rings and be inspired by the rich and brilliant colors that beets bring to salads. Or you might have picked up a lifelong aversion after too many canned pickled beets on a school lunch tray. Beets are a pretty polarizing vegetable. If you are among the haters, I’m going to do my best to turn the beet around for you.

Red and white beets

Why beets taste like dirt

Beets taste like dirt because they contain a compound called geosmin (meaning “dirt smell”). Geosmin is produced in abundance by several organisms that live in the soil, including fungi and some bacterial species in the genus Streptomyces. Humans are extremely sensitive to low concentrations of geosmin – so much so that we can smell it floating in the air after rain has stirred it up from the soil (Maher & Goldman, 2017). While people generally like that rain-fresh scent in the air, it’s less welcome elsewhere. For example, we perceive it as an off taste in water drawn from reservoirs with a lot of geosmin-producing cyanobacteria. In wines, geosmin contributes to cork taint. Continue reading

#Celery

It’s hard to get too excited about eating celery, but if you can manage to see a dip-drenched celery stick as a dynamically loaded cantilevered beam, then its stringy bits suddenly start to look like incredible feats of bioengineering. The mildest mannered member of the crudité platter turns out to be a misunderstood superhero.

If you are about to celebrate Thanksgiving, chances are good that you have a lot of celery in your immediate future. It shows up in dressing and cranberry relish and especially in leftovers, like turkey salad sandwiches. When I was growing up, my sister and I were tasked with picking the carcass for turkey hash, which, in our family, was basically turkey soup stretched with lots of celery and potatoes and never enough salt. Although frugal and nutritious, this one-pot crusade against food waste did not inspire a lifelong love of cooked celery. But you don’t have to like celery the food to admire its alter ego, celery the plant.

Leaves, not stems

Celery the food may not excite you, but celery the plant – the bundle of dynamically loaded cantilevered beams – is a biomechanical superhero worth exploring in the kitchen. Celery (Apium graveolens) is one of the clearest examples of how a plant’s life in the wild over tens of millions of years yielded anatomical adaptations that determine how we use it now. Because of its evolutionary responses to biomechanical challenges, it is now perfectly built to hold peanut butter or scoop dip, and when sliced, its crescent moon shapes are pretty in soup and chopped salads. On the other hand, its tough strings catch between teeth and are not easy to digest.

Celery stalks are the petioles (“stalks”) of compound leaves. They are not stems, in spite of widespread misrepresentation in elementary school lesson plans. They may look like stems to some people because they are thick and fleshy and have prominent veins running lengthwise through them. But there are several morphological clues to their leafy identity, including these: Continue reading

Botany Lab of the Month: Jack-O-Lantern

Happy National Pumpkin Day! Turn carving your Halloween Jack-O-Lantern into a plant dissection exercise.

IMG_7963

The first Jack-O-Lanterns were carved out of turnips in 17th-century Ireland. While the large, starchy hypocotyls (fused stem and taproot) of cruciferous vegetables are anatomically fascinating, this post will be about the stuff you are more likely cutting through to make a modern Jack-O-Lantern out of squash. Continue reading

Carrot top pesto through the looking glass

Isomers are molecules that have the same chemical constituents in different physical arrangements. Some terpenoid isomers have very different aromas and are important food seasonings. A batch of carrot top pesto led to an exploration of intriguing terpenoid isomers in the mint, carrot, and lemon families.

“Oh, c’mon. Try it,” my husband admonished me with a smile. “If anyone would be excited about doing something with them, I should think it would be you.”

The “them” in question were carrot tops, the prolific pile of lacy greens still attached to the carrots we bought at the farmer’s market. I have known for years that carrot tops are edible and have occasionally investigated recipes for them, but that was the extent of my efforts to turn them into food. My excuse is that I harbored niggling doubts that carrot tops would taste good. Edible does not, after all, imply delicious. My husband had thrown down the gauntlet, though, by challenging my integrity as a vegetable enthusiast. I took a long look at the beautiful foliage on the counter.

“Fine,” I responded, sounding, I am sure, resigned. “I’ll make a pesto with them.”

Carrot tops, it turns out, make a superb pesto. I have the passion of a convert about it, and not just because my carrot tops will forevermore meet a fate suitable to their bountiful vitality. The pesto I made combined botanical ingredients from two plant families whose flavors highlight the fascinating chemistry of structural and stereo isomers. Continue reading