Rapunzel

The rapunzel plant (Campanula rapunculus; Campanulaceae). Photo from Wikipedia.

The rapunzel plant (Campanula rapunculus; Campanulaceae). 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. 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 herehere, 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

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.

Apples: the ultimate everyday accessory

Infinity scarves? No. They won’t keep doctors away. Apples are the ultimate everyday accessory (fruit). Katherine explains where the star in the apple comes from. Could it be due to a random doubling of chromosomes? We also give readers the chance to test their apple knowledge with a video quiz.

Although apples are not particularly American – nor is apple pie – they color our landscape from New York City to Washington State, all thanks to Johnny Appleseed. Or so goes the legend. Everyone already knows a lot about apples, and for those wanting more, there are many engaging and beautifully written stories of their cultural history, diversity, and uses. See the reference list below for some good ones. There is no way I could cover the same ground, so instead I’ll keep this post short and sweet (or crisp and tart) by focusing on apple fruit structure and some interesting new studies that shed light on it.
Of course if you do want to learn more about apple history but have only 5 minutes, or if you want to test your current knowledge, take our video quiz! It’s at the bottom of this page.

Apple structure
Depending on your approach to eating apples, you may not actually consume any fruit at all. If you nibble the outer part, warily avoiding the core, then you might be missing the true fruit entirely. If, on the other hand, you eat all the way down to the core (or even eat the core itself like the Foodbeast guy) then you are definitely getting to the fruit.

Mature apple fruits in longitudinal and cross-section.  The "true fruit" is the part derived from the ovary.  It is visible in a cut apple as a ring of vascular tissue.

Mature apple fruits in longitudinal and cross-section. The “true fruit” is the part derived from the ovary. It is visible in a cut apple as a ring of vascular tissue. Click to enlarge.

Apples are pomes, meaning that what’s commonly considered the “true” fruit – the part derived from the ovary – is buried inside a large fleshy hypanthium that developed from other apple parts. The bulk of what we eat is that sweet and crunchy hypanthium (Greek for “under the little flower”). In spite of what some people assume, though, the actual ovary is not just the plasticky bits that surround the seeds and form the star in a cross-cut apple. Most of the ovary is fleshy and blends almost seamlessly into the rest of the apple. Its boundary is subtle, but you can see it in a cut apple as a ring of vascular tissue (veins) surrounding the core.

Pome-like fruits are found in apples, pears, quinces, loquats, and medlars, which are all members of the same clade (branch) within the rose family (Rosaceae).

Pomes of Heteromeles arbutifolia, with a penny for scale.  The fruit at bottom left still has an old petal attached at the distal end, illustrating the inferior position of the ovary.

Pomes of Heteromeles arbutifolia, with a penny for scale. The fruit at bottom left still has an old petal attached at the distal end, illustrating the inferior position of the ovary. Click to enlarge.

Also in the clade are typically wild-growing or ornamental plants such as hawthorne, cotoneaster, Heteromeles, Pyracantha, Photinia, and Raphiolepis. All of these species have flowers with inferior ovaries – ovaries buried within a hypanthium – and are unique within the rose family in this respect.

It’s easy to spot an inferior ovary because the leftover flower parts (or their scars) can be found opposite the stem on the mature fruit. In the rose family, a useful comparison is between apples and cherries or strawberries.

Cherry flowers have superior ovaries, visible within the floral cup.  Apple flowers' inferior ovaries are buried within a hypanthium and fused to it.

Cherry flowers have superior ovaries, visible within the floral cup. Apple flowers’ inferior ovaries are buried within a hypanthium and fused to it. Click to enlarge

The sepals and petals of a cherry generally fall off, but they leave scars in a ring close to where the stem meets the fruit. The sepals of a strawberry always persist, and petals can often be found on fresh berries, right around the stem.

By contrast, the floral bits of an apple are at the “bottom,” opposite the stem end. There you can see a ring of sepals surrounding a bunch of pollen-bearing stamens and sometimes even the styles that lead down to the ovary. Occasionally a shriveled petal remains there. Sometimes that little floral hole is filled with spider webs or dirt, but not as often as some people fear. And indeed I have noticed that some people do fear apples just a little bit, or at least eye them suspiciously. I don’t think we can blame the fate of Adam and Eve or the evil queen in Snow White for apples’ tainted reputation. I honestly think it’s anxiety over what might lurk in the little eye at the bottom of the fruit.

Sepals and a shriveled petal are visible at the flower end of an apple.

Sepals and a shriveled petal are visible at the flower end of an apple.

What we have learned from the apple genome
A pome is a type of fruit, and regular readers will know that fruit types are artificial categories with fuzzy boundaries and no regular or necessary relationship to evolutionary history or phylogenetic relatedness. That said, close relatives often produce the same type of fruit, and there are some fruit types restricted by convention to specific plant families or clades. Citrus fruits (hesperidia) are a good example of fruit type mapping perfectly onto a natural plant group.

Phylogenetic relationships among common fruits from the rose family.

Phylogenetic relationships among common fruits from the rose family.  Click to enlarge.

Within the rose family, the occurrence of pome fruits does reflect evolutionary history: pomes are present in only one clade, the apple tribe (called the Pyreae or Maleae). Intriguingly, this fruit type may be the result of a huge genetic shift within the family about 50 million years ago (Velasco et al. 2010). In 2010, a team of researchers published a draft of the apple genome, showing that the ancestor of the apple tribe experienced a duplication of its entire set of chromosomes (Velasco et al. 2010). The duplication was followed by an expansion and diversification of a set of genes (MADS-box genes) that control flower and fruit development by regulating the expression of other genes.

But how do a few genetic switches turn the ancestral dry fruit into an apple? It turns out that one of these MADS-box genes is particularly important for making a fleshy fruit, and that when it is experimentally turned off, the resulting fruit is dry. Even more impressive, though, is that the same gene is also required for other fruit qualities – exactly those qualities that would make a fleshy fruit attractive to animal dispersers: color, aroma, and sugar content (Ireland et al. 2013).  How do you like them apples?

All you wanted to know about apples in 5 minutes

References and further reading
Ireland, H. et al. (2013) Apple SEPALLATA1/2-like genes control fruit flesh development and ripening. Plant Journal 73: 1044-56.

Jacobsen, R. (2014) Apples of Uncommon Character: Heirlooms, Modern Classics, and Little-Known Wonders. Bloomsbury USA

Juniper, B.E. & Mabberley, D. J. (2006) The Story of the Apple. Timber Press

Pollan, M. (2001) The Botany of Desire: A Plant’s-Eye View of the World. Random House

Potter, D. et al. (2007) Phylogeny and classification of Rosaceae. Plant Systematics & Evolution 266:5-43.

Spjut, R. (1994) A Systematic Treatment of Fruit Types. NYBG. 

Velasco, R. et al. (2010) The genome of the domesticated apple (Malus × domestica Borkh.). Nature Genetics 42: 833–839

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

If it smells like onion or garlic, it’s in the genus Allium, and it smells that way because of an ancient arms raceThose 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

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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 Extreme Monocots

Coconut palms grow some of the biggest seeds on the planet (coconuts), and the tiny black specks in very good real vanilla ice cream are clumps of some of the smallest, seeds from the fruit of the vanilla orchid (the vanilla “bean”). Both palms and orchids are in the large clade of plants called monocots. About a sixth of flowering plant species are monocots, and among them are several noteworthy botanical record-holders and important food plants, all subject to biological factors pushing the size of their seeds to the extremes. Continue reading

Walnut nostalgia

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.

France 1154 Eng newAnnotation fullRes 2

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

An apple for the teacher

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

A biologist eating for two

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

Going bananas

What can make me feel less guilty about buying bananas? Science.

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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

Our Easter Bunny is a Botanist

Plant-dyed Easter eggs inspire a glimpse at the diversity of plant pigments.

(scene from Pride and Prejudice of dying ribbons with beets: https://www.pinterest.com/pin/374150681515259286/)

(scene from Pride and Prejudice of dying ribbons with beets)

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.

red cabbage

red cabbage

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

Origin stories: spices from the lowest branches of the tree

Why do so many rich tropical spices come from a few basal branches of the plant evolutionary tree?  Katherine looks to their ancestral roots and finds a cake recipe for the mesozoic diet.

I think it was the Basal Angiosperm Cake that established our friendship a decade ago.  Jeanne was the only student in my plant taxonomy class to appreciate the phylogeny-based cake I had made to mark the birthday of my co-teacher and colleague, Will Cornwell.  Although I am genuinely fond of Will, I confess to using his birthday as an excuse to play around with ingredients derived from the lowermost branches of the flowering plant evolutionary tree. The recipe wasn’t even pure, since I abandoned the phylogenetically apt avocado for a crowd-pleasing evolutionary new-comer, chocolate.  It also included flour and sugar, both monocots.  As flawed as it was, the cake episode showed that Jeanne and I share some unusual intellectual character states – synapomorphies of the brain – and it launched our botanical collaborations.

Branches at the base of the angiosperm tree
The basal angiosperms (broadly construed) are the groups that diverged from the rest of the flowering plants (angiosperms) relatively early in their evolution.  They give us the highly aromatic spices that inspired my cake – star anise, black pepper, bay leaf, cinnamon, and nutmeg.  They also include water lilies and some familiar tree species – magnolias, tulip tree (Liriodendron), bay laurels, avocado, pawpaw (Asimina), and sassafras. Continue reading