Pomegranates and the art of herbivore attraction

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Jeanne walks you through the botany you need to know to understand pomegranate fruit structure.  Jeanne’s definition of “need to know” is arguably a bit broad and includes a brief tour of the many different structures plants modify in order to entice herbivores, and at least one goddess, to disperse seeds. 

pomegranate fruit (persistent calyx and stamens visible)

pomegranate fruit (persistent calyx and stamens visible)

Pomegranates (Punica granatum, family Lythraceae, rosid order Myrtales) were one of the earliest domesticated plant species.  According to ancient Greek mythology, they even predate the seasons.  The story goes that Hades, god of the underworld, kidnapped his beloved Persephone, daughter of Demeter, goddess of the harvest.  Demeter’s grief over Persephone’s disappearance caused the crops to wither and wreaked havoc with humanity.  The plight of the starving masses coerced Zeus to convince Hades to return Persephone to her mother.  Before she left the underworld, however, Hades tricked her into eating a pomegranate seed, which bound her to evermore spend part of the year with her happy mother, during which time plants flourished, and part of the year in the underworld, during which time plants go fallow. Thus, seasons arose.

Pomegranate seeds

Pomegranate seeds

We can hardly blame poor Persephone for finding pomegranate seeds irresistible.  They look like faceted jewels and have a refreshing, tangy sweetness and a satisfying crunch. We have an additional reason to be drawn to pomegranates: even if they can’t help us understand the seasons, deciphering the structures of the beautiful pomegranate fruit helps us understand the diversity of mechanisms plants use to entice animals, including humans, to disperse seeds.  The delicious, nutritious or fibrous attractive structure is payment for the animal’s labor. As you will see in this post, there is no single anatomical recipe for creating the colorful, fleshy and/or juicy reward for a seed-dispersing herbivore, mortal or otherwise.  Many of the myriad flower, fruit and seed structures are variously promoted to the role of what is colloquially thought of as “fruit.” Continue reading →

Welcome to 2013, the International Year of Quinoa

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Can we call quinoa a grain? Why do people care?  Where did all these geese feet come from, and what does Ban Ki-moon have to do with it?  On long winter runs, Katherine’s mind wanders over such questions.

Quinoa seeds (Chenopodium quinoa)

Quinoa seeds (Chenopodium quinoa)

In the final two months of 2012, questions about quinoa and its status as a “grain” came up three separate times within my earshot.  This was odd in itself, but it launched a cascade of coincidences.  On a run near the baylands, my mind was idling back over those conversations, when I noticed for the first time a little weed along the trail, looking much like one of quinoa’s relatives, a saltbush.  (The crushed specimen I carried home in my shoe laces keyed out as Atriplex semibaccata, Australian saltbush.)  There is also a gorgeous and much larger saltbush species along the trail, and yet another relative, an edible Salicornia species (“sea beans”) that fills the marshy areas next to the bay.  Along with quinoa, spinach, beets, and chard, all of these species belong to the (former) goosefoot family – the Chenopodiaceae – which is now considered a branch nested within the Amaranth family.  Quinoa is a central member of this old family, belonging in the namesake genus Chenopodium. Continue reading →

The most interesting layer of wax in the world

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It’s high season for kale and apples, and Katherine just can’t stop talking about epicuticular wax

There is something nostalgic about kale and its softly glowing dusky cast that suits late autumn and early winter. It looks rustic and thick-skinned, steeled against falling temperatures and short days. It even shrugs off winter rains. Water beads up and rolls right off its leaves. Kale’s ageless still-life look is due to its extraordinary epicuticular wax, a legacy of the first plants to survive on dry land. Continue reading →

The holidays mean persimmons

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Hachiya persimmons, ripening

Hachiya persimmons, ripening

Jeanne discusses the biology behind the strange winter beauty of persimmon trees and demystifies why eating one before its time is an unpleasant experience.

The holiday seasons of my adult life increasingly include persimmons.  The ‘hachiya’ persimmons on my mother-in-law’s tree in California ripen around Christmas, beginning a conversation about what to do with them, and when they start showing up in the grocery store in late fall, I’m invariably drawn to the plump orange fruits with their handsome green calyxes.  I’ve now learned that persimmons, especially dried, are an important part of many new year celebrations throughout Asia, where there are thousands of persimmon varieties, but I only became acquainted with them when I moved from Denver to go to college in the Bay Area, where some of the Asian varieties are grown.  The bright orange plum-to-apple-sized persimmon fruits stay on the tree until well after the leaves drop in the autumn.  I paid little attention to the persimmon trees on campus—tall specimens of the ‘hachiya’ variety of Asian Diospyros kaki—until the leaves fell to reveal the scraggly branches laden with the orange orbs. Continue reading →

A brief history of gluten

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Victory with creating a gluten-free quick bread recipe inspires Jeanne to give you a brief primer on the evolutionary history of gluten within the grass family. 

We were perhaps a little too enthusiastic this fall in our apple picking at a local orchard and our acquisition of interesting squash at our farmer’s markets.  Our freezer now contains many bags of applesauce and squash puree.  We must now “do something,” as we say, with all of it, meaning use the purees as ingredients.  Lately I’ve been working on incorporating the purees into nutritious (low sugar, high protein, whole grain) quick breads.  On my doctor’s recommendation, that quick bread also needs to be gluten-free.  Increasing appearances of the phrase “gluten free” on restaurant menus and product labels are noble efforts to accommodate the needs of people who have celiac disease or other dietary sensitivities to gluten.  Baking without gluten is a challenge, as gluten is what gives wheat dough its elasticity and allows yeasted wheat bread to rise.  The internet makes gluten-free baking more accessible by the day, but I haven’t yet found someone else’s recipe that really does what I want, so I’ve been working on my own.  I’m fairly pleased with the latest result (below) and thought I would use the occasion to give you a brief evolutionary history of gluten and the botanical family that makes it:  the grasses. Continue reading →

Have a salad and relax: the Dipsacales trio

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The three edibles from the order Dipsacales (mâche, elderberry and valerian) inadvertently make their way into Jeanne’s evening.

As I added some dried valerian (Valeriana officinalis) root to my bedtime tea mixture, I realized that in doing so I had inadvertently incorporated the only three common edibles from the order Dipsacales into my evening:  elder, mâche, and valerian.  These three make the Dipsacales a lonely but interesting and delicious branch of the asterid group of eudicots (see our phylogeny page for phylogenetic contextualization of the asterids):

Orders in the asterids, Dipsacales in red

Orders with edibles in the asterids, Dipsacales in red

Continue reading →

Of sweet potatoes and putting down roots

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On a hunt for a traditional Thanksgiving tuber, Katherine discovers what it takes to root your own sweet potatoes.  Here she explains how sweet potatoes are put together, which anyone can observe in the kitchen.

The Sunday before Thanksgiving – the first Thanksgiving in 19 years that I have not spent with my family in Georgia – I was on a hunt for sweet potatoes.  Not a single one of my favorite vendors at the Mountain View farmers market grew them this year.  Finally, I questioned Luis Miranda of Wholeness Farms, who has always given me clear and patient explanations of many aspects of farming.  In his charming Nicaraguan accent, he simply said that sweet potatoes are a “long crop.”

Sweet potatoes of all kinds – orange, white, or purple, garnets, Beauregards, Georgia jets, and white stars – are members of the species Ipomoea batatas, in the morning glory family, Convolvulaceae. 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 →

Thanksgiving turnips and the diversity of the genus Brassica

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Jeanne briefly describes the cultivation history and botany of Brassica rapa, B. napus, B. nigra, and B. juncea to round out our cursory tour of the extraordinary genus Brassica.  Michelle offers a recipe highlighting a vegetable likely present at the first Thanksgiving:  the turnip, an exceptional cultivar of B. rapa.

White Tokyo turnips and purple-top turnips

Along with the turkey, stuffing, potatoes, green beans and cranberry sauce, Brussels sprouts have become something of a Thanksgiving staple.  None of these dishes, however, were part of the original harvest feast shared by the Pilgrims and Wampanoag in Plymouth Colony in 1621.  A close relative of Brussels sprouts, however, likely had an honored place at the table:  turnips.  The Pilgrims chose the tuberous vegetable to occupy precious cargo space in the holds of their ships bound for the New world and grew them in their Plymouth Colony gardens.  Turnips were probably also on most Americans’ Thanksgiving menus when President Lincoln made the holiday official in 1863.  During that first Thanksgiving turnips served as a sole representative of a genus, Brassica, that has one of the most impressive radiations of cultivated species on the planet.  Its extensive domestication happened primarily in Europe and Asia.  While Native Americans may have exploited weedy little native species in same family as the now-familiar Brassica (the mustard family, Brassicaceae), there is little evidence that they cultivated them or subjected them to artificial selection.

Row of turnips in the Monticello garden

Descriptions of turnips date to Alexander the Great’s vast kingdom, which spanned much of central Eurasia.  The vegetable’s domestication history earlier than that is not well known, but turnips likely made their way to western Europe from an Asian origin, along with several other well-known varietals of the same species, Brassica rapa.   In a previous post we discussed the numerous varieties of Brassica oleracea (including kale, collard greens, Chinese broccoli, Brussels sprouts, kohlrabi, cabbage, broccoli, and cauliflower).  The radiation of Brassica rapa into several morphologically variable domesticated vegetables across its broad native range in Europe, Asia and North Africa is almost as spectacular as that of B. oleracea.  Turnips, Italian rapini, and Asian cultivars bok choy, tatsoi, mizuna greens, napa cabbage, and purple mustard greens are all varieties of B. rapa.  In addition to B. oleracea and B. rapa, other important Brassica species in the human diet are Brassica napus (rutabaga and oilseed), Brassica nigra (black mustard) and Brassica juncea (mustard greens).  As such, the single genus Brassica alone accounts for a respectable fraction of the vegetables in a well-stocked produce section. 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 →