Who wants some green bean casserole?

Is there anything good about green bean casserole? Not much beyond its association with Thanksgiving, so Katherine will be brief and just keep you company in the kitchen in case you are stuck assembling said casserole.

Since this year is the International Year of Pulses, we have been focusing on legumes, whether they count as pulses or not. Green beans do not count as pulses, but only because they are eaten as tender and fresh immature whole fruits. The very same species (Phaseolus vulgaris), when allowed to mature, could yield black beans, white beans, kidney beans, or pinto beans depending on their variety – dry seeds that are perfectly good examples of pulses.

This Thanksgiving week we are going to welcome green beans into the fold and give them a special place. It’s too bad that Thanksgiving so often presents them out of the can, overcooked, with funky flavors, and buried in a casserole. Even Wikipedia promotes this peculiar tradition : “A dish with green beans popular throughout the United States, particularly at Thanksgiving, is green bean casserole, which consists of green beans, cream of mushroom soup, and French fried onions.”

And once again, international observers ask themselves what on earth are Americans thinking? That cannot be good for them. But in the American spirit of inclusivity we invite green beans of all sorts to our tables and try to learn something from them. So if you are preparing green beans this week, take heart, take up your knives, and take a closer look.

The outside of the bean

If your beans have already been trimmed and packaged or will be sliding their way out of a can, you can skip ahead to the next step. If you are making fresh beans, though, then you have much to be thankful for, not the least of which is the bunch of flowers before you.

Fresh green beans still carry bits of the flowers that they outgrew

Fresh green beans still carry bits of the flowers that they outgrew


The end of the bean you normally discard – the stem end – still has tiny remnants of the flower that bore the bean fruit. Look closely and you can usually see a pair of tiny little wing-like sepals, the outermost whorl of flower parts. On very fresh beans, there is often a little bit of membranous stuff just right near the sepals, and this is of course what’s left of the petals.

While the stem end carries the floral bits, it is tough and should be removed. Some people insist on removing the opposite end as well because it instinctively makes them uncomfortable. That curved tapering end is the elongated stigma and style where pollen grains landed and grew down into the ovary, carrying sperm cells and stimulating fruit development. It is very soft and I always leave it on, but the more squeamish among us may in fact want to remove any whiff of plant sex from their Thanksgiving tables.

The inside of the bean

Even pre-cut and canned beans are good for dissections and anatomy demonstrations

Even pre-cut and canned beans are good for dissections and anatomy demonstrations


Whether your beans are fresh, pre-trimmed, or canned, you can appreciate the inside of a green bean. Open it up carefully and you will see immature seeds inside, clinging to the inside of the bean fruit. The connecting structure, much like an umbilical cord, is a funiculus, which connects the developing seed to the placental tissue lining the fruit. On a mature dried bean, the scar from the funiculus is visible as a little eye on the concave side of the seed.

Alternative recipes

The traditional green bean casserole calls for cooking the beans in a matrix of cream of mushroom soup and topping them with French fried onions. It is possible to get all of these ingredients from a can, making it a cheap and fast dish. If you are fortunate enough, though, to have tender fresh beans on hand, you can serve them very simply with a bit of browned butter on top. Herbs and chopped almonds make them fancy. And for traditionalists, canned French fried onions do lend a nice fatty crunch to balance the freshness of the beans.

Jeanne and I have lots of other Thanksgiving themed posts here. Have a great holiday!

Buy me some peanuts!

As part of our legume series, the Botanist in the Kitchen goes out to the ballgame where Katherine gives you the play-by-play on peanuts, the world’s most popular underground fruit. She breaks down peanut structure and strategy, tosses in a little history, and gives you a 106th way to eat them. Mmmmm, time to make some boiled peanuts.

Baseball is back, and so are peanuts in the shell, pitchers duels, lazy fly balls, and a meandering but analytical frame of mind. Is this batter going to bunt? Is it going to rain? What makes the guy behind me think he can judge balls and strikes from all the way up here? What does the OPS stat really tell you about a hitter? Is a peanut a nut? How does it get underground? What’s up with the shell?  A warm afternoon at a baseball game is the perfect time to look at some peanuts, and I don’t care if I never get back. Continue reading

Botany Lab of the Month, Easter edition

Dying Easter eggs with homemade vegetable dyes today made for some superb kitchen botany. Making the dyes is easy, fun, and offers insight into the fascinating evolution of plant pigments.

2016-03-26 11.58.08

Pigments serve a variety of roles in plants. Many pigments protect plant tissues from sunburn and pathogens and herbivores or perform other physiological functions (see review by Koes et al. 2005). Most noticeably, however, their brilliant colors attract animal pollinators to flowers and seed dispersers to fruit. Humans are also interested in plant pigments, which color and sometimes flavor our food, are potentially medicinally active, and have been used as natural dyes and paints for millennia.

red cabbage

red cabbage

Today we made green dye from parsley, two different yellow dyes from turmeric and yellow onion skin, and three different pinkish-purplish dyes, from red cabbage, red onion skin, and beets. The basic recipe for all the vegetable dyes is the same: coarsely chop the vegetables, pour boiling water over it (about 2 cups vegetables or 1 tablespoon turmeric powder per quart of water), and stir in white vinegar (about a tablespoon per quart). Alternatively, put the chopped vegetables in a saucepan, cover with the water, and bring to a boil. You can either immediately add the hard-boiled eggs to the vegetable soup and let it sit for 12-48 hours, or you can let the vegetables steep for an hour and strain the vegetable solids out before adding the eggs and letting it sit.

The green color from the parsley comes from the pigment chlorophyll, a key component of the light-harvesting function of the photosynthetic apparatus. Grinding the parsley in the blender released the chlorophyll from the chloroplasts.

The spice turmeric comes from the rhizome (underground stem) of Cucurma longa (family Zingiberaceae), native to tropical southeastern India. Much (if not all) of turmeric’s yellow-orange color (and its distinctive earthy flavor) comes from its curcuminoids, natural phenols. These are likely defensive compounds that help the plant thwart herbivores and pathogens.

color courtesy carotenes

color courtesy carotenes

Curcuminoids are not widespread among plants, unlike other yellowish pigments, most notably the hydrocarbon carotenoids (xanthophylls and carotenes, including vitamin A precursors). The yellow-orange color of the yolks inside our Easter eggs came from the xanthophylls lutein and zeaxanthin that the chickens obtained from their food, ultimately from plant sources. Xanthophylls provide sunscreen to leaves. Carotenes have photosynthetic roles, but they’re mostly known for the color they give to many plant structures. Most carotenes confer yellow or orange color, but the carotene lycopene is bright red and is a primary pigment of tomatoes, red carrots, watermelons, and papayas. Although carotenoids are common, I don’t know much about their use as a dye. The yellow color from the yellow onion skins came not from carotenoids but from oxidative byproducts of flavonoid pigments, notably quercetin.

Red onion color from anthocyanins and quercetin

Red onion color from anthocyanins and quercetin

Red cabbage and red onion get their purple color from anthocyanins, the most common purple and blue pigments found in nature. Beets, however, get their red and yellow colors from betalain pigments, which replace anthocyanins, and to some extent carotenoids, as a pigment source in most families in the botanical order Caryophyllales (see our Food Plant Tree of Life phylogeny page for details on phylogenetic placement of the Caryophyllales; and see this excellent article for the comparative biology of anthocyanins and betalains within the Caryophyllales). That may initially sound obscure, but there are a lot of food plants in the Caryophyllales, all with betalains instead of anthocyanins (See our Food Plant Tree of Life list).

Betalains turn salads with beets bright pink

Betalains turn salads with beets bright pink

Extra Credit: At some point in your primary education you may have done a chemistry lab (like this one) using red cabbage-derived anthocyanins to learn about pH, as the anthocyanins can display an impressive range of color depending on pH. The acid (vinegar) in the dye may complicate this plan, but I wonder if there is a way to take advantage of the pH-sensitivity of anthocyanin pigments in dye making.

Botany Lab of the Month, Superbowl Edition

In 2016, the International Year of Pulses, we’ll be writing a lot about pulses (dried beans and peas), and we’ll also tackle the huge and diverse legume family more broadly. This weekend Katherine kicks things off with February’s Botany Lab of the Month: beans and chickpeas for your Superbowl bean dip and hummus.

The species name of Cicer arietinum means "ram's head."

The species name of Cicer arietinum means “ram’s head.”

Beans are a bit like football: a boring and homogeneous mass of protein, unless you know where to look and what to look for. In this lab, we’ll make the smashing of beans into bean dip or hummus much more interesting by taking a close look at some whole beans before you reduce them to paste. The directions are very detailed, but this whole lab can be completed in the time it takes to explain the onside kick.

Of course, if you have only pre-mashed refried beans in your pantry, it’s too late. Then again, if you are using canned refried beans for your recipe, you are probably not living in the moment or sweating the details right now. That’s OK. Go watch the game and let us know when someone scores. Continue reading

Botany Lab of the Month (Oscars edition): potatoes

This month we introduce a new feature to the Botanist in the Kitchen: Botany Lab of the Month, where you can explore plant structures while you cook. In our inaugural edition, Katherine explains why she would like to add her nominee, Solanum tuberosum, to the list of white guys vying for Best Supporting Actor.

In one of this year’s biggest and best movies, Matt Damon was saved by a potato, and suddenly botanists everywhere had their very own action hero. It’s not like we nearly broke Twitter, but when the trailer came out, with Damon proclaiming his fearsome botany powers, my feed exploded with photos of all kinds of people from all over the world tagged #Iamabotanist. The hashtag had emerged a year earlier as a call to arms for a scrappy band of plant scientists on a mission to reclaim the name Botanist and defend dwindling patches of territory still held within university curricula. Dr. Chris Martine of Bucknell University, a plant science education hero himself, inspired the movement, and it was growing pretty steadily on its own. Then came the trailer for The Martian, with Matt Damon as Mark Watney, botanizing the shit out of impossible circumstances and lending some impressive muscle to the cause. The botanical community erupted with joyous optimism, and the hashtag campaign was unstoppable. Could The Martian make plants seem cool to a broader public? Early anecdotes suggest it’s possible, and Dr. Martine is naming a newly described plant species (a close potato relative) for Astronaut Mark Watney.

In the film, that potato – or actually box of potatoes – was among the rations sent by NASA to comfort the crew on Thanksgiving during a very long mission to Mars. After an accident, when the rest of the crew leaves him for dead, Watney has to generate calories as fast as he can. It’s a beautiful moment in the movie when he finds the potatoes. In a strange and scary world, Mark has found a box of old friends. They are the only living creatures on the planet besides Mark (and his own microbes), and they are fitting companions: earthy, comforting, resourceful, and perpetually underestimated. At this point in the movie, though, the feature he values most is their eyes. Continue reading

Winter mint

This is our second of our two contributions to Advent Botany 2015. All the essays are great!

An early image of candy canes. From Wikipedia

An early image of candy canes. From Wikipedia

The candy cane, that red- and white-striped hard candy imbued with peppermint oil, is a signature confection of the winter holidays. Peppermint has a long history of cultivation and both medicinal and culinary use. Infusions of the plant or its extract have been used for so many hundreds of years throughout Europe, North Africa and Western Asia that the early history of peppermint candies, including cane-shaped ones, is murky. Fortunately, the biology behind peppermint’s famous aroma is better known than the story of how it came to be a Christmas staple. Continue reading

Sugar

This is our first of two contributions to Advent Botany 2015.

Sugar plums dance, sugar cookies disappear from Santa’s plate, and candied fruit cake gets passed around and around. Crystals of sugar twinkle in the Christmas lights, like scintillas of sunshine on the darkest day of the year. Katherine and Jeanne explore the many plant sources of sugar.

Even at a chemical level, there is something magical and awe-inspiring about sugar. Plants – those silent, gentle creatures – have the power to harness air and water and the fleeting light energy of a giant fireball 93 million miles away to forge sugar, among the most versatile compounds on earth, and a fuel used by essentially all living organisms.

Sugar naturally occurs in various chemical forms, all arising from fundamental 3-carbon components made inside the cells of green photosynthetic tissue. In plant cells, these components are exported from the chloroplasts into the cytoplasm, where they are exposed to a series of enzymes that remodel them into versions of glucose and fructose (both 6-carbon monosaccharides). One molecule of glucose and one of fructose are then joined to form sucrose (a 12-carbon disaccharide). See figure 1.

Sugars: glu, fru, and sucrose

Figure 1.

Sucrose is what we generally use as table sugar, and it is the form of sugar that a plant loads into its veins and transports throughout its body to be stored or used by growing tissues. When the sucrose reaches other organs, it may be broken back down into glucose and fructose, converted to other sugars, or combined into larger storage or structural molecules, depending on its use in that particular plant part and species. Since we extract sugar from various parts and species, the kind of sugar we harvest from a plant, and how much processing is required, obviously reflects the plant’s own use of the sugar. Continue reading

Throwback Thursday Thanksgiving feast

We’ve got several posts in the pipeline – and this year we are contributing to Advent Botany – but meanwhile, we bring you posts from the past to nerd-up your kitchen as you cook. Don’t forget, nothing deflects from an awkward personal revelation or a heated political conversation like a well-placed observation about plant morphology.

We wish you a happy, healthy Thanksgiving!

Continue reading

How giant pumpkins got so big: A Q&A with Jessica Savage

Biologist Jessica Savage answers a few of our questions about her research on the physiology behind giant pumpkin size.

In October 2014, a giant pumpkin grown by Beni Meier of Switzerland tipped the scales at 1056 kilograms (2323 pounds) and set a new world record for the heaviest pumpkin ever weighed. Modern competitive pumpkin growers have been imposing very strong selection on pumpkin size for decades. Pumpkin fruit size keeps climbing, and old records are broken every year or two (Savage et al. 2015).

Beni Meier with his 2014 record-winning 2323-pound pumpkin, presumably a specimen of the Atlantic Giant variety of Cucurbita maxima. Photo from here.

Continue reading

Triple threat watermelon

Will seedless watermelons make us superhuman or turn our children into giants?  Hardly, but they do give home cooks the power to count chromosomes without a microscope.   Just a knife or a hard thunk on the sidewalk are enough to get a watermelon to spill its genetic guts.

If you were reading a Hearst Corporation newspaper in late 1937, you might have thought humanity would eventually be swallowed up by giant carnivorous plants, unwittingly unleashed by uncontrolled biotechnology.  The San Francisco Examiner reported on November 21st of that year that the discovery of an “elixir of growth,” meant that “…science may at last have a grip on the steering wheel of evolution, and be able to produce at will almost any kind of species…”  including “…a plague of man-eating ones.”  In 1937 Americans had much more important things to worry about, just as we do now.  Still, that discovery may in fact have threatened one cherished aspect of the American way of life by triggering the slow demise of late summer state fair watermelon seed spitting contests.  It doubtlessly paved the way for seedless watermelons, and in 2014 the total harvest of seedless watermelons on American farms – nearly 700 thousand tons – outweighed the seeded watermelon harvest more than 13 to 1 (USDA National Watermelon Report). A similar pattern is emerging this year.  Is there no stopping the attack of the seedless watermelons?

Image from microfilm of an actual page in the San Francisco Examiner, published Sunday November 21, 1937. Found in the Media and Microtext Center of Stanford University Libraries.

CLICK to read. Image from microfilm of an actual page in the San Francisco Examiner, published Sunday November 21, 1937. Found in the Media and Microtext Center of Stanford University Libraries.

And more important, how is it even possible to get seedless fruit from an annual plant?  From a plant whose only mode of reproduction is through those very seeds?  From a plant that cannot make suckers as bananas do and cannot be perpetuated endlessly through grafts like fruit trees and vines?   Such is the challenge posed every single year by watermelons, but thanks to the “elixir of growth” discovered by Albert Blakeslee and subsequent work by Hitoshi Kihara, one of the most prominent agricultural geneticists of the 20th century, the world has an elegant solution. Breeders continually improve the varieties available, and consumer demand keeps growing, yet seedless watermelon production methods have remained essentially unchanged for three quarters of a century. Continue reading