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.
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
Posted in Flavor, The basics, Uncategorized
Tagged diversity, Jeanne L. D. Osnas, Katherine Preston, phylogeny, plant, species, sugar, sugar beet, sugarcane, sweet
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!
A close relative of The rapunzel plant (Campanula rapunuloides). Photo from Wikipedia.
I never suspected that I’d learn something about edible botany by indulging my 3-year-old’s princess obsession, but I have. According to the Brothers Grimm, Princess Rapunzel is named after the cultivated vegetable of the same name, growing in a witch’s garden. The wording of the story suggested to me that the Grimms’ contemporaries would be familiar with the plant as a vegetable, that it wasn’t a fantastical invented thing. Apparently rapunzel was a popular vegetable in the Grimm’s Europe.
Formally the rapunzel plant is Campanula rapunculus, native from southwestern Asia through central Europe to North Africa. The genus Campanula contains upwards of 500 species of what are commonly called bluebells, bellflowers, or harebells, widely distributed throughout the northern hemisphere. Many if not most of those species have edible flowers, leaves and roots (see links here, here, here and here). The Brothers Grimm don’t specify which parts of the plant were particularly enticing to Princess Rapunzel’s mother.
Our princess, in the Tangled-inspired dress from Santa
Many species in the closesly-related genus Adenophora also have edible roots, leaves and flowers. These genera add a taxonomic family, Campanulaceae, to our list of taxa with culinary species. Campanulaceae joins the sunflower family (Asteraceae) as culinary families in the order Asterales. Rapunzel seeds are for sale, and it can grow in Anchorage, where we will be moving this spring. My little Rapunzel will have to beat the moose to it in the garden next summer. It’s so interesting to me that this was once considered a common, mainstream cultivated vegetable, but now it’s considered a fringe edible plant or something to be “wildharvested.” It’s fun to learn about plants that were once widely cultivated for food but have since fallen out of fashion. Wonder why that is.
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 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
Posted in Uncategorized
Tagged allium, amaryllidaceae, angiosperm, Brassica, Brassicaceae, chemistry, chive, convergence, crucifer, defense, garlic, greens, Jeanne L. D. Osnas, leek, onion, phylogeny, ramp, recipe, sulfur, vegetable
Walnuts may not seem like summer fruits, but they are – as long as you have the right recipe. Katherine takes you to the heart of French walnut country for green walnut season.
Public domain, via wikimedia commons
English walnuts do not come from England. The English walnut came to American shores from England, but the English got them from the French. The (now) French adopted walnut cultivation from the Romans two millennia ago, back when they were still citizens of Gallia Aquitania. Some people call this common walnut species “Persian walnut,” a slightly better name, as it does seem to have evolved originally somewhere east of the Mediterranean. But the most accurate name for the common walnut is Juglans regia
, which means something like “Jove’s kingly nuts.” I think of them as queenly
nuts, in honor of Eleanor of Aquitaine, because if any queen had nuts, she certainly did. During her lifetime the Aquitaine region of France became a major exporter of walnuts and walnut oil to northern Europe, and it remains so more than 800 years later. Continue reading
With her fellow educators in mind, Katherine tells a story of virtual botany in the dining hall and letting students be teachers.
When we botanists in the kitchen are quiet for a little while, it usually means we are focusing all of our attention on our day jobs. Like a garden, the academic calendar has a rhythm that cannot be ignored, and from April through June, I pour most of my time and creative energy into my small seminar class, where we dig into the evolutionary and ecological connections between humans and plants across many time scales and topics. It’s a fun class and the debate is usually lively, but because the journal articles we discuss are often dense and technical, I sometimes worry that we are squelching some opportunities for joy. Continue reading
This is a bit tangential to our usual fare, but I think it’s fun, and you may as well. A friend of mine, Cara Bertron, edits the creative and delightful quarterly compendium Pocket Guide. I submitted this image, entitled “A biologist eating for two,” for the current issue, which is themed “secret recipes.” It’s a cladogram of the phylogenetic relationships among all the (multicellular) organisms I (knowingly) ate when I was pregnant with my now two-year-old daughter. Continue reading
What can make me feel less guilty about buying bananas? Science.
Trying to get the banana back in the peel
I am genuinely curious about the size of the fraction of carbon in my two-year-old that is derived from bananas. When we have bananas in the house, which is most of the time, she eats at least part of one every day. She loves them peeled, in smoothies, dried, in banana bread, or in these banana-rich cookies, which sound like they shouldn’t be good but are totally amazing. Bananas are inexpensive and delicious, and making nutritious food with them gives me a sense of parental accomplishment. Nonetheless, always I feel a niggling sense of guilt whenever I plunk a bunch of bananas into the shopping cart. Prosaic though it may be, most of this is contrition inspired by the “local food” movement. I know that very little is benign about the process responsible for bringing these highly perishable tropical fruits to my table for less than a dollar a pound. The remainder of my remorse is conviction that bananas should not be taken for granted. Not only is banana history and biology interesting, but the banana variety in our grocery stores, the Cavendish, is in danger of commercial extinction. There isn’t an easy solution to the problem or an obvious candidate for a replacement variety. The history of the Cavendish’s rise, and the biology behind its current peril, makes for a good story. Continue reading
Plant-dyed Easter eggs inspire a glimpse at the diversity of plant pigments.
Pigments serve a variety of roles in plants. Many pigments have physiological roles within plants and protect plant tissues from sunburn and pathogens and herbivores (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, in part because they color and sometimes flavor our food, are potentially medicinally active, and have been used as natural dyes and paints for millennia.
Last weekend I made some natural Easter egg dyes from turmeric and beets (I followed these instructions). We also considered making dyes from red and yellow onion skins or red cabbage, but we kept it simple. This handful of plants used to make cheap, easy, homemade dyes can give us some insight into of the chemical and evolutionary diversity of plant pigments. Continue reading