Epiphany Hidden in Fava Beans

January 6 is Epiphany, not a week into the new year and its tradition causes many Louisianians to abandon any resolutions related to gustatory moderation. I’m referring, of course, to the King Cake. In modern tradition, a King Cake is a circular pastry made of Danish-type dough, filled with fruit spread, cream cheese, flavored sugar or some combination thereof topped with an additional layer of icing decorated with purple, yellow and green colored sugar. There is a plastic baby, representing Jesus, inside, and the eater finding the slice with Jesus is charged with purchasing the next King Cake. This continues throughout the Carnival season. It truly is the decadence of Mardi Gras captured in cuisine.

King Cake via Wikimedia

Traditionally, the King Cake has slightly more humble origins. It has always been associated with Epiphany, the church holiday marking the visitation of the Three Kings to see the baby Jesus, but the recipe was not always the refined sugar freight train it is today. Think more bread and dried fruit. Before the advent of plastic trinkets, the baby Jesus was symbolized by the fava bean.

Vicia faba via Wikimedia

The fava bean (Vicia faba) or broad bean is a hardy legume that has been in cultivation for thousands of years. This low maintenance crop has been a source of quality protein for the human diet for just as long. Its class connotations have waxed and waned throughout history, but for some people it can trigger a potentially deadly anemia. The condition is so tightly linked to fava beans, it is known as favism.

The king is dead?

Favism is really just one manifestation of a deficiency in the enzyme Glucose-6-Phosphate Dehydrogenase (G6PD). This is the rate-limiting enzyme within the pentose phosphate pathway, which the cell uses to generate reducing power in the form of NADPH and glutathione as well as 5-carbon sugar groups to use as building blocks of DNA or amino acids. People can display a range of G6PD deficiency levels. This depends on the type of mutation and the relative amounts of the mutant G6PD expressed. This mutation is X-linked, which means you inherit it from your mother. Because males inherit only one X chromosome copy, if they get a defective version, they will always display some level of favism. Female carriers of the G6PD mutation can also show some deficiency as well. Even though female carriers contain two X-chromosomes (of which has a normal G6PD and the other has the mutant version), cells only need to use one copy. Relatively early in development, one copy of the X chromosome in each cell is silenced. Thus, there is a random inactivation of one copy of the G6PD gene in each cell; in some cases the mutant version will be inactivated, in others the normal version. This creates the potential for a range of G6PD deficiency to be observed even when the woman has one copy of a normal G6PD.

So how can fava beans wreak such havoc on basic human metabolism? Fava beans synthesize the alkaloid glycoside, vicine. This substance is a particularly powerful trigger for oxidative damage to the cells. In the red blood cells of G6PD deficient individuals, there’s just not enough reducing power within the cell to protect them from the build-up of hydrogen peroxide and other damaging reactive oxygen species. Consequently, the red blood cells burst open resulting in acute anemia.

Vicine chemical structure via Wikimedia

Long live the king!

How have this metabolic mutation and food crop coexisted for so long? It seems like nature and/or agriculture would select for one or the other. There are other beans out there, ‘Am I right?’ And how could a mutation in such a critical enzyme in central metabolism accumulate in more than 400 million people worldwide? The answer lies within another disease- malaria. The incidence of G6PD deficient versions is higher in individuals of African and Mediterranean descent. There is a working hypothesis that some level of G6PD deficiency offers a fitness advantage over normal individuals when it comes to malaria infections. When the Plasmodium parasite infects red blood cells, some amount of oxidative stress occurs. Because G6PD deficient individuals have a sensitivity to this stress, their red blood cells burst eliminating the parasite’s home. When you consider a population of red blood cells within a G6PD deficient individual infected by the parasite, it’s advantageous to be able to sacrifice some red blood cells in order to give the immune system the chance to clear the parasite. In normal individuals, all red blood cells are easy targets for the parasite, which can enter them and hide more effectively from the host’s immune system. It should be noted though that some malarial treatments given to G6PD deficient patients can be toxic themselves as they also generate a fair amount of oxidative stress.

G6PD deficiency is a relatively benign condition when it is diagnosed and certain oxidative triggers are avoided. So in the same way that it’s good to uncover a plastic Jesus in your King Cake, it’s good to know your G6PD variety. If you’re G6PD deficient, it’s not so good to uncover a fava bean. However, the complicated hidden interrelatedness of each of these things will lead to new epiphanies in malarial infections and their treatment.

Johnna

References and links:

http://en.wikipedia.org/wiki/King_cake

http://en.wikipedia.org/wiki/Bolo_Rei

http://en.wikipedia.org/wiki/Rosca_de_reyes

http://en.wikipedia.org/wiki/Vicia_faba

http://www.hort.purdue.edu/newcrop/cropfactsheets/fababean.html

http://en.wikipedia.org/wiki/Glucose-6-phosphate_dehydrogenase_deficiency

http://www.ncbi.nlm.nih.gov/pubmed/10916676

http://www.ncbi.nlm.nih.gov/pubmed/18177777

http://en.wikipedia.org/wiki/Vicine

http://www.ansci.cornell.edu/plants/toxicagents/vicine.html

http://g6pddeficiency.org/wp/g6pd-deficiency-home/favism-2/#.VKxIUyvF-Xg

http://food.unl.edu/allergy/metabolic-food-disorders

http://anthropology.ua.edu/bindon/ant475/g6pd/G6PD.pdf

http://www.ncbi.nlm.nih.gov/pubmed/24675047

http://www.ncbi.nlm.nih.gov/pubmed/23534950

For the First Time in Forever: Vernalization

Next up in the Frozen series… we’re talking about flowering for the first time in ‘forever’ (really, just after winter). Here’s the Disney version for your reference.

FRIGIDA’s gone, so’s FLC

Winter is over? Can it be?

We need to transcribe a thousand different genes

For months we’ve waited in dormancy

Halted all pluripotency

Finally, it’s time to make some scenes!

There’ll be actual real live flowers

It’ll be totally great

I’m so ready for this activated state!

‘Cause for the first time in forever

There’ll be flow’ring, there’ll be growth

For the first time in forever

Translating AP1 and LFY both!

It must be the gibberellic acid

There’s active meristematic zones

‘Cause for the first time in forever

FLC is gone

I can’t wait to bloom, everyone!

What if I meet… the one?

This Spring imagine me petals and all,

Fetchingly vining up the wall

My flowers a delicately shaped vase

Ooh! I suddenly see him buzzing by

A striped pollinator that can fly

I’m gonna shove some pollen in his face!

But then we trade pollen and nectar

Which is completely strange

Not like when FLC is in detectable range

For the first time in forever

There’ll be flowers, there’ll be sun

For the first time in forever

I’ll be making AP1

And I know it is totally crazy

Excitement over meristems

But for the first time in forever

There’s activity in them

[FLC:]

Don’t let them out, don’t turn them on

Winter could still go on and on and on

Repress, turn off, it’s not time to grow,

Make one wrong move and get killed by snow

[FLC:] Is it only for today?

[FT:] It seems like Spring today!

[FLC:] It’s agony to wait

[FT:] It’s agony to wait

[FLC:] The VRNs are saying open up the gate

[FT:] The gate

[FT:] For the first time in forever

[FLC:] Don’t turn them on, don’t let them out

[FT:] I’m getting what I’ve waited for

[FLC:] Be the regulator the plant needs about

[FT:] A chance to change my stagnant world

[FLC:] Repress

[FT:] A chance to pollinate!

[FLC:] Repress, turn off, don’t let them out

I know it all ends in autumn,

So it has to start today

‘Cause for the first time in forever

For the first time in forever

Nothing’s in my way!

Flowering is important for plants because it’s how they reproduce. So, they need to have ways of ensuring that this process occurs under conditions that are most favorable for seed production. Plant species solve this problem in a variety of ways. Some annual plants avoid harsh conditions altogether and complete their life cycle within a single warm growing season. Others must find ways of going dormant during the freezing winter months and wait out the season until spring comes back. Plants integrate information on both day-length and duration of cold temperatures so they are not fooled into flowering on a random warm day in winter.

Under any conditions, the transition to flowering requires an elaborate set of gene expression changes so that cells achieve the proper developmental fate. The perennials and winter annual plants that require a cold period of dormancy prior to the flowering transition have an extra layer of regulation to ensure the transition occurs at the right time. Plants accomplish this with a set of gene regulators, some promoting the floral transition and others repressing it. These tiered layers of control allow for seemingly binary (on/off) switches to become a way of fine-tuning the development of flowers in these plants.

It’s not unlike the opposing personalities of Anna and Elsa in the movie Frozen. The gene FLC functions to keep plants from flowering, while genes like AP1, SOC1, FT, and LEAFY turn on genes to promote flower production. In perennials and winter annual plants, FRIGIDA serves to keep plants from flowering through the work of FLC until a certain amount of winter temperatures have passed. The genes VIN3, VRN1 and VRN2 act to let the plants know that enough winter weather has occurred and the hold on flower development (via FLC and FRI) can be let go. The way that the repression system works is also an interesting case. It’s not that these proteins physically block transcription of certain genes; these repressors leave covalent marks on the genome and the histone proteins whose job it is to organize the DNA within the cell nucleus. It takes some effort on the part of the activators to undo these marks to subsequently turn on the necessary genes.

Major players controlling flowering in plants. Pointed arrows mean activation or promotion of the next downstream thing, while blocked lines indicate repression of the next step in the pathway.

It’s interesting to note that all of the genes mentioned in the above paragraph are gene transcription regulators of one variety of another. This highlights a continuing theme in how pathways for development or environmental acclimation are controlled. There are a small set of regulators which control sets of other genes that are also regulators or that actually do the necessary biochemical work. These regulators work together to integrate environmental information (in this case-temperature, light, day-length) and keep developmental programs in check. Scientists tend to identify these factors pretty early in their investigations of these big questions, usually because mutants in these important regulators have obvious defects in the process of interest.

However, I have to admit, this drives me crazy as a biochemist. I want to know what’s going on beyond the nucleus in these processes. Sure, we may know a lot about what conditions turn these regulators and other genes on and off, but we know very little about the physical mechanisms by which plants sense the winter temperatures and time how long they’ve persisted. What is the actual ‘winter sensor’ in plants? How is it different from the cold sensor that plants use for cold acclimation on the timescale of hours or just a few days? How does this winter sensor differ among varieties with different ‘chill requirements’ before they flower and make fruit in the spring?* These components remain a mystery, but one that plant scientists are furtively working to solve.

Vernalization (the plant biology word of the day) is the acquired ability of a plant to flower after a cold season. For our perennials and winter annual plants, the passing of sufficient winter (as measured by the mysterious ‘winter sensor’ and regulated by VIN3, VRN1, VRN2, and FRI) gives these plants the ability to burst forth in flowers in the spring. Even though these regulators have a protective role for the plants in keeping them from trying to flower in the freezing winter, once their control is finally released, the flurry of activity associated with flower development is akin to a grand celebration after what seems like a lifetime of seclusion. Upon flowering, it’s all about reproduction. When it comes to plants, there’s not even a pretense of modesty; they have no problems trading pollen grains with a pollinator they have just met.

A number of economically important agricultural crops, like wheat, cabbage, carrots and most fruit trees, have vernalization requirements for flowering. Understanding how this process works is critical for getting the most out of these plants where they are grown and expanding the arable ranges for these crops. It may be some time before plant biologists make a Honeycrisp apple tree I can grow in Louisiana, but even modest adjustments to vernalization requirements to staple crops like wheat may be needed to accommodate predicted climate changes.

For more on how plants remember winter, check out this post over at The Quiet Branches.

Johnna

*This is why apple trees (with varieties requiring 400 – 1000 chill hours) don’t flower efficiently and produce fruit in a place as far south as Baton Rouge, LA (~200 – 300 chill hours), but figs (requiring only 100 – 200 chill hours) do.

References and Links:

http://www.azlyrics.com/lyrics/idinamenzel/forthefirsttimeinforever.html

http://en.wikipedia.org/wiki/Vernalization

http://www.newphytologist.org/app/webroot/img/upload/files/amasino.pdf

http://www.plantcell.org/content/16/10/2553.full

https://www.jic.ac.uk/staff/caroline-dean/vernalization.htm

http://plantcellbiology.masters.grkraj.org/html/Plant_Growth_And_Development11-Physiology_Of_Vernalization.htm

http://www.weigelworld.org/research/projects/floweringtimes

http://www.pnas.org.libezp.lib.lsu.edu/content/111/27/10001.abstract

http://www.ndsu.edu/pubweb/~mcclean/plsc731/homework/kim-et-al-vernalization-winter-%20and-the-timing-of-flowering-in-plants.pdf

Do you want to make a plastid?

Next up in the Frozen series… Do you want to make a plastid? Here’s the snowman version from Frozen for your reference.

Plant cells…

Do you want to make a plastid?

Come on, differentiate

Time to photosynthesize

Special things to metabolize

C’mon they need a fate

Those used to be proplastids

And now they’re not

We hope genetics tells us why!

Do you want to make a plastid?

It doesn’t have to be a chloroplast

Do you want to make a plastid?

Some grana stacks green and tall?

I think some development is overdue…

Environment gives you cues

From the nucleus transcription calls!

(Induce there GLKs)

It gets a bit confusing

All these proteins whizzing by

Translocation…

TIC, TOC, TIC, TOC, TIC, TOC

Chromoplasts get lots of color

With all these carotenoids

Amyloplasts store starches

For all the tissues underground!

Do you want to make a plastid?

It could even be a tannosome

Yes, etioplasts are in there

In the dark since who knows when

Shine the light to start,

The nucleus is there for them,

No longer inside meristems,

Time for some changes to begin!

They do so many functions,

Biochemistry

What can’t plastids do?

Do you want to make a plastid?

Well, if you are a plant cell, the answer to that refrain is always, “Yes!” Plastids are specialized organelles in plants that perform a wide array of specialized biochemistry. The most well-known and recognized of these are chloroplasts. These subcellular compartments are packed full of the thylakoid membranes and enzymes necessary to convert light into sugars. Chloroplasts perform other important biochemical reactions including the synthesis of starches and fatty acids as well as the assimilation of nitrogen into amino acids.

The chloroplast by User:Miguelsierra, adapted by User:Vossman via Wikipedia

There are other types of plastids made in plant cells for other specialized purposes. There are chromoplasts, which are full of carotenoid and other pigments giving them distinctive colors. The cells of tomato flesh, carrots and rose petals contain this type of plastid. Of course, pigments don’t do much good in root tissues. You may not find chloroplasts or chromoplasts there, but they do contain leucoplasts (loosely defined as non-green plastids used for storage of starches and oils). Storage-type plastids aren’t relegated to the roots. Recently other types of plastids have been identified, which specialize in the synthesis and storage of distinctive metabolites. Tannosomes have recently been characterized as specialists in tannin storage. A phenyloplast was also recently described in vanilla fruit as the storage location for vanillin precursor metabolites. In fact, the range of biochemical specialization that plastids perform strains their traditional nomenclature and definitions. As scientists learn more about them, the divisions between traditional types seems to blur. It seems that plants can make them as specialized as they need to be along a gradient of biochemical functions.

Types of plastids by Mariana Ruiz Villarreal LadyofHats via Wikipedia

Plant cells have definitely capitalized on the versatility of the plastid organelle structure to ensure dedicated locations for all manner of biochemical reactions and/or storage of their products. This is no small task. It requires the coordination of genes in two different genomes (that of the plant cell nucleus as well as a small genome in the plastid), trafficking of proteins throughout the cell, sensing of environmental cues, and synchronization with the overall plant developmental program. It’s enough to make any project manager run out of color-coded post-its and lose track of scheduled task times. Here are the highlights:

First of all, plastids do not exist in their mature forms in plant seeds and developing meristem tissues, but as immature and developmentally-flexible proplastids. These proplastids may not be special biochemists in their own right, but they have the potential to become any kind of plastid the plant cell needs. Consequently, proplastids have to know whether they are inside a root cell, petal cell or leaf cell. This means that plastid differentiation (aka development to maturity) must be coordinated with the development of the rest of the plant. Scientists are beginning to learn more about how this works, but this research is difficult since we’re talking about tiny, unremarkable pro-organelles within small portions of tissue. It’s a universal rule of cell biology that studying on small things is much more difficult than studying large things. Genetics has provided some new insights as to which genes have control over this developmental process. Transcription factors like the Golden-like (GLK) family of proteins have been identified as major players in this process, turning on suites of other genes to trigger proplastid development into mature plastids.

Of course, a lot of plant cell and plastid development is tied to environmental cues like light intensity. For example, plants can develop up to a point in darkness, but that doesn’t mean those cells have the same mature chloroplasts present in light-grown plants. Dark-grown plant cells contain plastids termed etioplasts, which are somewhat more differentiated than proplastids but not quite chloroplasts. Upon illumination, etioplasts quickly whip up thylakoid membranes and the photosynthetic machinery and get to the work of photosynthesis.

Plastid development and maintenance requires a large protein migration within plant cells. While plastid genomes make a number of their proteins, they do not make all of their resident proteins. Many essential proteins must come from genes transcribed in the plant cell nucleus and translated in the cytoplasm or endoplasmic reticulum. Thus, plant cells have an elaborate system of trafficking proteins to the proper cellular destination. This is true for all kinds of eukaryotic cells, but plant cells have extra organelles to distinguish among relative to animal cells. For those proteins with final destinations in the chloroplast, they have signals within their sequences that target them there. When they arrive at the chloroplast, they must pass through the surrounding double membranes using the Translocon of Outer Chloroplast Membrane (TOC) and the Translocon of Inner Chloroplast Membrane (TIC). In addition to the large influx of proteins that must be deposited upon initial development, the nucleus continues to provide essential proteins to the chloroplasts throughout their lifetime. It’s a constant flurry of activity maintained by two-way communication between the nucleus and chloroplast such that each organelle knows the biochemical status of the other.

Development into a mature plastid type isn’t the end of the line. There is still some developmental plasticity allowing certain plastids to convert into other plastid types. I’ve mentioned before that chloroplasts convert to chromoplasts in ripening fruit, as can be seen in the characteristic color change of green, unripe fruits into bright yellows, oranges and reds. Chloroplasts also provide the starting point for the development of other plastids specializing in storage of certain biomolecules. Plant cells also have ways of recycling the valuable contents of their plastids when cells and tissues reach the end of their lives (think autumn leaf color-change). As you might expect, this process requires more changes in gene transcription, protein synthesis and membrane structure orchestrated by the cell nucleus in response to more environmental and developmental cues.

Finally, proplastids and plastids of all types have ways of replicating themselves within plant cells. In this way, as plant cells divide each new daughter cell will contain roughly equal numbers of plastids. It wouldn’t be very good if a certain cell line within a tissue ran out of plastids. As much as plastids rely on the nucleus to full development and function, the nucleus cannot spontaneously create plastids from nothing. This wrinkle adds another layer of complexity to plastid biology. It means plastids must have some way of dividing themselves within the cells, and when plant cells divide, they must have some way of equally segregating the multiple plastids between the two new cells.

Basically, plastids are a lot of work for plant cells to make and maintain. However, these high-maintenance organelles are worth it given the biochemical rewards they offer. Scientists are only beginning to understand how plants make, maintain and recycle their plastids. Pieces of the complex system are studied by plant biologists all over the world and will likely keep them busy for many years to come.

 

Johnna

 

References and Links:

http://www.disneyclips.com/lyrics/frozenlyrics2.html

http://en.wikipedia.org/wiki/Plastid

http://link.springer.com/book/10.1007%2F978-3-540-75376-6

http://www.springer.com/life+sciences/plant+sciences/book/978-94-007-5723-3

http://www.uoguelph.ca/~itetlow/publications/assets/pdf/BY008-03-60-125.pdf

http://pcp.oxfordjournals.org/content/51/10/1601.long

http://www.ncbi.nlm.nih.gov/pubmed/23851381

http://www.ncbi.nlm.nih.gov/pubmed/23876238

http://journal.frontiersin.org/Journal/10.3389/fpls.2014.00124/abstract

http://onlinelibrary.wiley.com/doi/10.1046/j.1365-313X.2002.01390.x/full

http://aobblog.com/2013/09/announcing-brand-new-cellular-organelle-tannosome/

http://www.ncbi.nlm.nih.gov/pubmed/24683183

Carnations: The Blanket of Champions

Today is the running of the Belmont Stakes, the third jewel in thoroughbred horseracing’s Triple Crown. This mile and a half race is known as the ‘Test of Champions,’ sorting out the speedy flashes in the pan from those that can race with endurance. Like the other two jewels of the Triple Crown, the Belmont Stakes has its own floral tradition.

Blanket of white carnations on the Belmont Stakes winner Credit: Craiglduncan via Wikimedia commons

White Carnation Credit: Dysepsion via Wikimedia Commons

White carnations are the prize of the victor. Wow. Carnations. Dianthus caryophyllus. The ubiquitous ruffled flower used as filler in almost every floral arrangement. Personally, I am not a fan of these blooms and feel they should be relegated to their place in history as boutonnieres of the 1970s. Yes, I said it. I’m sure I’m in the minority view since carnations are economically important worldwide in the floral trade. Still, you’d think the Belmont and potential Triple Crown champion would be adorned in something more lavish like orchids or plumerias to go along with the silver bowl made by Tiffany and Co. Yet it is the fundamental characteristic of the carnation as a cut flower- endurance- that deems it the most fitting ornament for the winner. Their soft colors and delicate ruffled petals belie their stamina in the vase compared to other blooms, and this is why carnations have been a mainstay of floral arrangements for centuries to the point of being unremarkable, tacky even. Analogous hardiness and perseverance in the racehorses is critical for success in the Belmont and celebrated in the form of the carnation flower.

Carnation line drawing Credit: Pearson Scott Foresman via Wikimedia Commons

As in racehorse breeding, ornamental plant breeders are seeking to combine the desirable traits of flash and fortitude. I’ve mentioned in several other posts about the genetics behind new color patterns and flower forms, but the ultimate champions in the floral industry must have stamina in the vase. This isn’t something that plants have a natural tendency to do. The purpose of flowers is to provide a desirable visual attractant to pollinators; usually insects- plants could really care less about what people think of them.* Once pollination occurs, the flower’s job is done and there’s no need for the plant to invest the energy into maintaining firm colorful petals. Thus, after pollination the flowers begin the program of senescence, in which certain cells and tissues die and fall off of the plant. Plant scientists and horticulturists are working to understand the factors involved in order to find ways to short-circuit the process and keep cut flowers alive longer in our arrangements. The complex biochemical pathways that control floral senescence make this task about as difficult as breeding a Triple Crown winner.**

White carnations are also said to represent love and luck. Sure there is a lot of love poured into the Belmont Stakes contenders. No one will discount the chance events that aided the campaigns of the three-year-old horses up to this point, but there is a great amount of dedication, training and hard work by both species contributing to success on the racetrack.

White carnation Credit: Takkk via Wikimedia Commons

 

 

“I believe luck is a concept invented by the weak to explain their failures.” –Ron Swanson

 

 

 

Whatever the factors contributing to the victory, the winning horse will get a blanket of white carnations painstakingly assembled by the official florist of the New York Racing Association, Tony Green and his team the day of the race. The thousands of the best-looking carnation flowers were chosen earlier this week and have been soaking in water for the past 48 hours to ensure maximum plumpness. 700 of them will be meticulously glued onto the green fabric to form the blanket for today’s winner. That’s not the only blanket that will be made today. Florists will actually be assembling another blanket to go onto the statue of Secretariat, track and world-record holder for one and half miles on dirt. Actually, there will probably even be a third carnation blanket because Secretariat’s first carnation blanket will likely wilt in the humidity before the end of the day and need to be replaced. Not even carnations have the endurance to withstand those conditions.

 

Johnna

*Michael Pollan might disagree. Plant-human interactions have changed quite a bit and once humans become artificial plant pollinators and propagators, the selective pressure changes tremendously.

**But remember there are some advantages of plants vs. thoroughbreds when it comes to manipulating genomes. Last I checked, transgenic technology is not allowed nor is it available for thoroughbreds.

References and Links:

http://en.wikipedia.org/wiki/Belmont_Stakes

http://www.belmontstakes.com/

http://www.belmontstakes.com/history/carnationblanket.aspx

http://www.belmont-stakes.info/carnations.php

http://www.thewire.com/national/2014/06/your-guide-to-the-belmont-stakes/372364/

http://www.americasbestracing.net/en/the-latest/abrv/2014/6/5/exploring-the-belmonts-blanket-of-carnations/

http://gardeningsolutions.ifas.ufl.edu/giam/plants_and_grasses/flowering_plants/carnations.html

http://en.wikipedia.org/wiki/Dianthus_caryophyllus

http://web.extension.illinois.edu/cfiv/homeowners/090219.html

http://www.proflowers.com/blog/history-and-meaning-of-carnations

http://www.oardc.ohio-state.edu/joneslab/manuscript_PDF/Woodson_Jones_ACTA.pdf

May Bouquet: Tulips

April showers have brought May flowers… to the blog. Today’s post is one of a May Bouquet series focused on flowers one might find in a bouquet. Y’know, leading up to Mother’s Day today! Think of these posts as daily reminders with wonderful suggestions on ways to honor the mothers in your lives.*

Credit: Wikipedia

Today’s post is tip-toeing through the tulips. They rank at the top of lists for most popular cut flowers and bulb plants in gardens. The flowers provide intense spring color in such uniformity that they are easy to incorporate into any arrangement- vase or plot.

Tulip Credit: John O’Neill via Wikipedia

These flowers originated in central Asia, but their introduction to Europe in the late 1500s created such a stir in the Netherlands it has come to be known as ‘tulip mania.’ The Dutch economy was good at the turn of the 17^th century, so people had time to invest in aesthetics. The recently introduced tulip was the perfect medium with its dazzling capacity for intense color on a consistent form. New color varieties were introduced with names like Viceroy and Semper Augustus and demand caused their prices to skyrocket.

Semper Augustus print via Wikipedia

However, basic tenets of tulip biology made the economic speculation craze dangerous and untenable. While tulips are perennials that can be grown from bulbs year after year, it takes as along as 4-6 years to go from seed to a bulb large enough to flower. This makes introducing new varieties slow, even when vegetatively propagating them from bulb offsets. Plus, as they are flowers, their beauty is by definition fleeting. They bloom for a short time during the spring then exist as bulbs for the remainder of the year.

Furthermore, the most desired tulips were the ‘broken’ varieties with blooms containing streaks of two colors. During this period, the streaks were not due to some inheritable genetic mutation, but infection with Tulip Breaking Virus. It caused pleasing visual appeal, but also weakened its host. Eventually, the bulbs weakened to the point of not being able to flower or produce additional bulb offsets. Thus, the most expensive tulips in history have gone extinct. Many of the streaked varieties available on today’s market are the result of stable genetic mutations that affect flower coloration, but not the vigor of the plant. There are only a few truly ‘broken’ varieties left (like Absalon), which are infected with TBV, but for some reason the infection has not manifested itself beyond the effects on flower color pattern.

The Viceroy Credit: Wikipedia

So just how much money are we talking about? More than anyone in modern times has spent at a garden center for a single bulb. For example, records indicate that a bulb for ‘The Viceroy’ sold for approximately ten times the annual earnings of a skilled craftsman. The peak of tulip bulb speculation was the winter of 1636-1637. Of course, at this time tulips are only bulbs with no flowers at all, hardly things that look worthy of fortunes. Tulip trading was a futures market, and contracts were written based on what traders thought the bulbs would be worth to consumers at spring planting time. At some point that winter, people came to their senses. The first few that cashed in their contracts set off a selling frenzy that caused the bottom to drop out of the market.

In the end, fortunes were lost and some were left with lots of worthless bulbs. I’m sure their beauty that spring was just salt on the wound. It was even difficult to eat their losses. Tulip bulbs taste awful and when not prepared correctly, they are poisonous. They are really only a food source of last resort in extreme situations, like the Nazi occupation of the Netherlands during World War II.

Today’s tulip markets are more rational, but still huge business in floriculture. New colors, shapes and patterns are being developed, but the source of the broken tulips, Tulip Breaking Virus, is no longer coveted, but eliminated. The ultimate damage this pathogen does to vigor of the tulip bulbs outweighs the production of any desirable color patterns. The spread of this infection is controlled by using pesticides and other measures to reduce aphids on the tulips that spread the virus as they eat on one plant then another. TBV is detected by experts trained to spot the symptoms in the tulip plants in the field. Infected plants are removed and destroyed. A new report out this year describes an instrument capable of scanning plants in the field for TBV to improve this laborious process.

Flaming Parrot Tulip Cultivar Credit: PierreSelim via Wikipedia

So, if tulips find their way into your bouquet today, enjoy them- just don’t go crazy.

Credit: McBeth via Flickr

Johnna

*Maybe you’ve learned something about plants along the way. Maybe these posts have helped you remember to pick up flowers for the mothers in your life. But let me just add, if one of those mothers still has small children, say that you sired or otherwise claim, make sure your bouquet also includes species like folded laundry, extra sleep, cooked meal, clean kitchen and bathroom. These varieties, while difficult to cultivate without the help of a mother, will surely reap you returns greater than those seen during tulip mania.

References and Links:

http://en.wikipedia.org/wiki/Tulip

http://aggie-horticulture.tamu.edu/floriculture/hort429/lecture/bulbs.pdf

http://en.wikipedia.org/wiki/Tulip_mania

http://www.investopedia.com/features/crashes/crashes2.asp

http://en.wikipedia.org/wiki/Tulip_breaking_virus

http://www.thetulipgallery.com/view/173

http://ppdl.purdue.edu/PPDL/weeklypics/4-18-11.html

http://www.historicflowerbulbs.com/Spring%20Flowering/Tulips.html

http://www.liliumbreeding.nl/Tulipa_breeding.pdf

http://www.liliumbreeding.nl/LA%2010170%20Tulipa.pdf

http://extension.umd.edu/sites/default/files/_docs/programs/ipmnet/FS837TulipsAsCutFlowers-Commercial.pdf

http://www.eattheweeds.com/tulips-famine-food-appetizer-assistant-2/

http://www.sciencedirect.com/science/article/pii/S1537511013000883#

May Bouquet: Lilies

May Bouquet: Lilies

April showers have brought May flowers… to the blog. Today’s post is one of a May Bouquet series focused on flowers one might find in a bouquet. Y’know, leading up to Mother’s Day this Sunday. Think of these posts as daily reminders with wonderful suggestions on ways to honor the mothers in your lives.

It wasn’t that long ago, Lilium longiflorum was featured on this blog, but today we are moving out of the pots and into the vases where a wider world of lilies awaits. And it’s a wild world out there. Check out these different forms.

 

Orange Lily in full bloom showing pollen covered stamens, Ontario, Canada. June 2002. Credit: Relic38 via Wikipedia

Lilium superbum Credit: Arx Fortis via Wikipedia

Lilium tsingtauense Credit: Klaus Goldbeck via Wikipedia

Oriental hybrid Credit: Hardyplants via Wikipedia

Lilium monadelphum Credit: Arnold Trachtenberg via Wikipedia

These blooms burst with celebrate and all of these colors and shapes deserve to be seen, but it has only been relatively recently that lilies have gained ground in the cut flower industry. Some lilies had large fragrant blooms, but faced downward on the stem. Other varieties had smaller but more colorful flowers that were easier for florists to work with. In the late 1970s, Leslie Woodriff, a dedicated lily breeder developed the Stargazer hybrid lily. The combination of genetics he stumbled upon combined the most desired traits into a single plant- bold color, delightful fragrance and upward-facing bloom. In the world of cut lilies, the Stargazer is still the most popular with more than 36 million sold annually.

Stargazer Lily Credit: Dogmadic via Wikimedia

The success of the Stargazer lily opened the floodgates for lily breeders to experiment with other hybrids. Today there are more than 7000 registered lily varieties to choose from when it comes to designing bouquets for all occasions. The new classes of hybrids bring together color patterns, fragrance and bloom shapes in all combinations. One of the newer famous lily varieties to come out of the labors of master Dutch hybridizers is the ‘Robina,’ a large dark pink lily. There’s still no transgenic technology involved, but a lot of science still goes into cultivating the new hybrid seeds that would otherwise have a difficult time growing in standard conditions.

 

Robina Liliy
Credit: Caroline via Flickr

Of course, there is one thing that still plagues the use of lilies in floral arrangements for formal occasions- the prodigious amounts of bright yellow to dark brown pollen on their large anthers. When it dusts off onto fabrics like white tablecloths or expensive wedding gowns, it can cause a stain that is quite difficult to remove.* Of course, this is not a ‘problem’ for the plants, only for the humans that choose to enjoy them. In fact, the pollen is quite essential for the lilies because it is necessary for their sexual reproduction. Pollen is the plant-equivalent of sperm. Hopefully this doesn’t ruin the whole bouquet-thing for you, but in case you hadn’t made the connection yet… bouquets are just plant reproductive organs on display.** So, yeah, about that lily pollen on your wedding dress, “Ugh. and Eww.” Nobody wants that stain.

Regardless of the utility of pollen to the lilies, scandalous stain potential has prompted extreme measures to get rid of the pollen. Some florists may perform the tedious task of clipping off the anthers from each open lily flower, but I know exactly how many lily flowers (one, maybe two) I would have to emasculate to start thinking, “There’s gotta be a better way!” So, lily breeders have been on the genetic hunt for varieties that do not produce pollen. There are some varieties on the market and generally this produces sterile flowers. (Not to worry because they are perennials that can grow from bulbs, these plants can still be propagated.) Some varieties, like Elodie, make normal-looking lilies that just appear to have completely bare anthers. Other varieties have a double petal pattern, in which the extra set of petals bends upward to the center of the bloom modestly enclosing all of the anthers and stamens.

Elodie Lily
Credit: Diana Beideman via Flickr

Suffice it to say that there are many lilies to choose from for your bouquet, and breeders are ensuring that there will be even more choices in the future. Just enjoy the colors and the fragrance and try not to focus so much on their biological utility.

 

Johnna

*FYI- brush it off with something dry, adding moisture will cause the stain to set.

**What can I say, plant reproductive parts are just more beautiful than those of any other kingdom of life. It also adds a deeper meaning to the giving of bouquets in celebration of holidays like Valentine’s day, Mother’s Day, weddings and anniversaries, but I’m just here for the plant science.

References and Links:

http://en.wikipedia.org/wiki/Lilium

http://www.sierraflowerfinder.com/en/c/lilies/11?page=1

http://www.sierraflowerfinder.com/en/f/lilies/asiatic-lilies/154?page=1&flt=0

http://www.lilies.org/

https://store.extension.iastate.edu/Product/rg313-pdf

http://www.mikesbackyardgarden.org/lilygen.html

http://www.flowerbulbs.cornell.edu/forcing/cut_lilies.htm

http://www.icangarden.com/document.cfm?task=viewdetail&itemid=9278&categoryid=0

http://www.icangarden.com/clubs/GDHS/document.cfm?task=viewdetail&itemid=7358&categoryid=0

http://www.flowershopnetwork.com/blog/newsletter-june-2008/

http://www.stargazerperennials.com/Lilium_Stargazer_Lily.html

http://wimastergardener.org/?q=StargazerLily

http://cindydyer.wordpress.com/tag/leslie-woodriff/

http://phillipoliver.blogspot.com/2011/07/perhaps-most-famous-lily-of-all.html

http://wcfcourier.com/lifestyles/home-and-garden/gardening/plants_shrubs_and_trees/hello-gorgeous-lily-breeders-introduce-new-beauty-vigor/article_da6016bd-0a23-5cb4-bb86-7998650d1516.html

http://www.lilybreeding.com/

http://davidsgardendiary.wordpress.com/2012/09/03/pollen-free-lilies/

http://www.hartsnursery.co.uk/Pollen-Free-Lilies/

May Bouquet: Hibiscus

April showers have brought May flowers… to the blog. Today’s post is part of a May Bouquet series focused on flowers one might find in a bouquet. Y’know, leading up to Mother’s Day this Sunday. Think of these posts as daily reminders with wonderful suggestions on ways to honor the mothers in your lives.

Pink Hibiscus
Credit: Johnna Roose

Today’s featured flower is the hibiscus. These large and colorful blooms demand notice and are the opposite botanical personality of the shrinking violet. They are synonymous with the tropics, prominently featured on Hawaiian print fabrics, more so than even palm trees and pineapples. In fact, a yellow hibiscus native to the islands (Hibiscus brackenridgei) is the official state flower of Hawaii. Hibiscus plants make great additions to any garden, but if you plan to keep them for multiple growing seasons, they are easier to manage as potted plants. This is because they are sensitive to cold and will have to be protected in most climates during the winter.

Yellow Hibiscus
Credit: Johnna Roose

Yellow Hibiscus
Credit: Johnna Roose

If you are looking for a plant to turn any area into a tropical oasis, hibiscus is the right choice. They are available in all types of bold colors- yellow, pink, red, and coral. Hibiscus breeders and hybridizers have been busy generating new varieties in all shapes, sizes and color combinations. There are a large number of distinct species of Hibiscus, but the majority of the ornamental varieties found in garden centers are likely to be Hibiscus rosa-sinensis. Genetically, it is a polyploid. This means it has multiple copies (>2) of genomes and not just the single copy from each parent (diploid) like we are. This wealth of genetic material means that these plants have a seemingly bottomless bag out of which to pull tricks when it comes to flower form and color. Crosses and hybrids of plants can yield all kinds of color combinations; thus, when grown from seed, you never know what you’ll get. If you like surprises, that’s great. If you had your heart set on a particular color, then go with a grafted plant that has been propagated to give the type you would like. Check out some of the links below for more hibiscus flower eye candy.

Red Hibiscus Bloom
Credit: Monica Russell

Can’t pick just one favorite color or combination? You may not have to. Some plants have several different varieties grafted onto main rootstock bases to give you a single plant with red blooms on one stem, yellow on another and coral on yet another.

Multicolored Hibiscus
Credit: Monica Russell

Don’t these flowers just look good enough to eat? Well, you can. The flowers are used as the base for hibiscus tea and dried flowers are also candied and used as garnishes. Humans aren’t the only species that appreciate the taste of the hibiscus. These plants are also attractants for butterflies and birds. If your landscape is frequented by deer, prepare to go to battle to protect your beautiful and tasty blooms from them as well.

Pink Hibiscus
Credit: Johnna Roose

If you’re inspired to grow your own, check your local garden centers now. For my Baton Rouge area friends, we’ve apparently just missed (May 4^th) the Red Stick Hibiscus Society’s show and sale, but the shows of the New Orleans and Acadiana Chapters are still to come this month. Or if you are really serious about hibiscus, you may just want to join the American Hibiscus Society. FYI, their national convention will be held in Lafayette, LA in June of this year. Check here for details.

 

Johnna

References and Links:

http://en.wikipedia.org/wiki/Hibiscus

http://en.wikipedia.org/wiki/Hibiscus_rosa-sinensis

http://www.garden.org/plantguide/?q=show&id=2133

http://www.statesymbolsusa.org/Hawaii/flower_hibiscusyellow.html

http://en.wikipedia.org/wiki/Hawaiian_hibiscus

http://www.exotic-hibiscus.com/

http://www.hiddenvalleyhibiscus.com/misc/history.htm

http://www.hiddenvalleynaturearts.com/acatalog/multi.htm

http://www.trop-hibiscus.com/index.html

 

A thorn by any other name

When dangerous situations arise for plants, the choice between flight or fight is a simple one. They abide by the stand your ground law and always fight. Such a lifestyle choice means that plants employ a variety of weapons to stave off extinction. Thorns are one of the more obvious botanical defenses. Their appearance is a clear warning not to trample and no herbivore would like a mouthful of sharp spines.

No one will disagree that thorns hurt, but would a thorn by any other name hurt as much? In everyday language usage, we may refer to any sharp plant appendages as thorns, but botanically these sharp protrusions can be thorns, spines or prickles. Their true names are tied to the tissue from which they developed. Thorns are derived from shoot material and are actually branches modified to terminate in a sharp point. Spines are leaves modified to be entirely spike-shaped or barbed along the edges (like holly). Everything else is considered a prickle. So, roses actually have prickles along their stems, not real thorns. Regardless of what term is used, the effect on herbivores and other careless animals that would otherwise trample them is the same.

(A) Thorns and spines are derived from shoots and leaves respectively, and have vascular bundles inside. (B) Prickles (like rose prickles) don’t have vascular bundles inside, so they can be removed more easily. Credit: CASF via Wikipedia

Botanically speaking, Poison’s Bret Michaels was incorrect when he sang “Every rose has its thorn.” I’m willing to give him a pass on accuracy because I’m scared to know how he would’ve rhymed prickle in the subsequent line. Beyond this, modern horticulture is proving him wrong on the entire premise of his song- that all beautiful and good things must have a dark and dangerous side. This may work for the image of a rock star, but plant breeders are diligently trying to disentangle the pretty from the prickly. Some thornless roses are commercially available, but the trait isn’t always stable and thorns can appear when these plants experience certain environmental conditions. For now, the genetics of rose prickles remains a mystery, but eliminating this trait will continue to be the focus of rose breeders and plant scientists.

Johnna

 

References and Links:

http://en.wikipedia.org/wiki/Thorns,_spines,_and_prickles

http://www.britannica.com/EBchecked/topic/593317/thorn

http://blogs.cornell.edu/naturalistoutreach/files/2013/09/Hlusko_TeacherResourceGuideFinal-w0ph2e.pdf

http://waynesword.palomar.edu/ecoph30a.htm

http://www.docsdrive.com/pdfs/ansinet/pjbs/2003/1712-1719.pdf

http://smoothtouchroses.com/hist.html

http://agriliferesearch.tamu.edu/files/2011/01/rose_breeding.pdf

The Science of the Shamrock

Happy St. Patrick’s Day! Everyone else may be drinking at the pub and kissing everyone else that claims to be Irish today, but let’s talk about the foliage behind the festivities. The patron saint of Ireland used the typical shape of the shamrock as an illustration of the Holy Trinity. The Latin name of the white clover genus, Trifolium, literally means three leaves.

Spot the four-leaf clover
Credit: Kristie Phillips

More four-leaf clovers
Credit: Kristie Phillips

As symbolic as the common foliage form may be, we all know that the four-leaf clover is a symbol of good luck. This is because the four-leaf variety is quite rare (about 1/10,000). I am not a lucky person and have never personally found a four-leaf clover. All of the pictures of 4+-leaf clovers in today’s post are from my friend Kristie Phillips* whose special superpower is finding rare clovers with more than three leaves. Check out this link for more science-based tips on finding your own four-leaf clover. If you are just interested in the statistics behind finding a four-leaf clover check out these posts. Even rarer are clovers with more than 4 leaves. The world record for most leaves on a shamrock is 56!

Five-leaf clovers
Credit: Kristie Phillips

You may be wondering what the underlying reason is for these deviations from the typical three-leaf form. You are not alone. Other plant scientists have had the same question. They have been working on determining the genetic basis of leaf number and other valuable ornamental traits in clover. This has been slow going because clover is an allotetraploid, which is a hybrid that has four times the number of chromosomes of 1n gamete cells. With these complex genetics, clover prefers to outcross giving a wide range of phenotypic forms. Surely, there is a genetic component to the multiple leaf form of clover- some rare recessive gene that is infrequently unmasked to give four-leaf clovers. Scientists were able to map this trait along with a few other desirable ornamental traits. This was a real breakthrough for breeders that are seeking to enhance the frequency of these traits in clover used as ornamental bedding plants. Note, that genetics isn’t the entire answer because environmental conditions also contributed to the frequency of the four-leaf foliage variety. Will the four-leaf clover be any less lucky once its frequency is increased to 1/100 or 1/10? I’m not sure, but maybe I’ll finally be able to find one.

Even more than six-leafed clover
Credit: Kristie Phillips
I told you she had a superpower!

However, an exact gene controlling this trait has not yet been identified, but scientists may not be that far away from tracking it down. The genome for red clover was published earlier this year and I’m sure it won’t be long before breeders and scientists will correlate the markers used by breeders to the assembled sequences within the genome. The molecular mechanism for four-leaf clovers is still a mystery for now, but understanding how this works will provide new insights into plant development. Breeders have long sought after ways of controlling patterns in complex leaves for ornamental plants and the secrets of the shamrock may prove useful toward attaining this goal.

These types of scientific discoveries make for good blog fodder on days like today, and maybe I’ve tricked some of you into learning some plant science**. However, some of you out there may be wondering if your tax dollars were really spent determining what makes clovers have four leaves. Before you get all grumpy cat on scientific research spending, let’s talk about how important clover really is. Even if you could care less about ornamentals (and the market value of our nation’s garden centers would disagree with you), clover still has a lot to offer from a functional standpoint. We may not regularly eat shamrock salads, but clover is an important forage crop for animals we like to eat. According to the USDA, it’s “the most important pasture legume.” It’s nutritious and delicious herbivores like to eat it. As a nitrogen-fixing crop, it adds this essential nutrient back into the soil using gaseous nitrogen from the atmosphere making it useful as a cover crop in pastures and crop fields. Therefore, any traits that can be added as markers on a genetic map of this important crop are useful for breeding strategies in general. That kind of luck isn’t just frivolous, it’s practical.

Johnna

*All photos were used with permission. Copyright Kristie Phillips, all rights reserved.

**All part of my larger plan for world domination.

References and Links:

https://getd.libs.uga.edu/pdfs/tashiro_rebecca_m_200905_ms/tashiro_rebecca_m_200905_ms.pdf

https://www.crops.org/publications/cs/abstracts/50/4/1260

http://www.guinnessworldrecords.com/records-1/most-leaves-on-a-clover/

http://blog.minitab.com/blog/real-world-quality-improvement/the-odds-of-finding-a-four-leaf-clover

http://blog.minitab.com/blog/adventures-in-statistics/the-odds-of-finding-a-four-leaf-clover-revisited-how-do-some-people-find-so-many

http://www.noble.org/news/news-releases/2010/10-030/

http://onlineathens.com/stories/071210/uga_674945701.shtml

http://www.sciencedaily.com/releases/2010/06/100624141000.htm

http://www.newscientist.com/article/dn19112-plant-nurseries-in-clover-after-finding-fourleaf-gene.html#.UyIkIIXFm_t

http://www.scientificamerican.com/video/how-science-can-help-you-find-four-leaf-clover-video/?utm_source=twitterfeed&utm_medium=twitter

http://en.wikipedia.org/wiki/Trifolium_repens

http://en.wikipedia.org/wiki/Four-leaf_clover

http://plants.usda.gov/factsheet/pdf/fs_trre3.pdf

Chocolate

“Life is like a box of chocolates. You never know what you’re gonna get.” Forrest Gump

akira yamada via Wikimedia commons

As you’re peering into your heart-shaped box of chocolates this Valentine’s Day, you may have questions. Which one will have the caramel? Which one has almonds? Coconut? How do I avoid that weird fruity ganache I hate? Well, trial and error is always a strategic possibility, but if you’d prefer fewer surprises those boxes usually have a key of some sort to tell you which flavor corresponds to which confection. It’s probably in that paper layer that you tossed aside as soon as you opened the box.

But these can’t be your only questions. I know you come here for the plant science. So let’s explore the tree behind the treats.

Theobroma cacao with fruit Credit: Luisovalles via Wikipedia

Chocolate is prepared from the seeds of the tree Theobroma cacao. This small, shade-loving tree is native to the rainforests of Central and South America. It prefers a tropical environment and is cultivated in areas located within 20 degrees of the equator. Flowers develop on the trunk of the tree and once pollinated, they develop into yellow-orange oblong fruits that look more like Nerf footballs than anything you might want to try to eat.* Each pod contains between 20 and 60 seeds. The seeds are high in fat and contain a variety of aromatic chemicals that provide the beloved flavor. Check out the videos below that take you from the tropical tree to the treats in your Valentine’s Day box.

Theobroma cacao flowers Credit: Kurt Stuber via Wikipedia

Now, I could stop writing this post at this point because I’m sure the majority of my readers have already learned more than they thought they possibly could about cocoa trees (unless of course you are a plant scientist or chocolatier). However, in my opinion, chocolate is all about over-the-top decadence. So prepare to overindulge in the next level of chocolate science.

Cross-section of cacao fruit Credit: Keith Weller, USDA ARS via Wikipedia

There are three main cultivars of Theobroma cacao used for chocolate production. The vast majority of commercial chocolate production (80 – 90%) uses ‘Forastero,’ which provides high yields and disease resistance. It’s not the highest quality, but can be produced in large quantities and blended with other varieties to improve flavor. The ‘Crillo’ variety produces the finest quality chocolate, but is the rarest comprising only 5-10% of world production because of low yields and less robust trees. The ‘Trinitero’ variety accounts for 10 – 15% of world production and is a hybrid of the other two varieties. Clearly, these different varieties will command different prices in the world chocolate trade. However, the seeds have indistinguishable appearances. Given the large number of small stakeholder farmers and the middlemen of the cocoa trade, it can be a problem for chocolate producers to know what they are getting (or how much they should pay for it). Researchers have recently developed a genetic test that can be performed on cocoa bean samples to establish their true identity and value. This type of testing has clear benefits to chocolate producers in terms of quality control and financial savings and it may be implemented as standard practice someday soon. Consumers, like Forrest Gump, may still be wondering about the contents of their holiday confections, but nanofluidic single nucleotide polymorphism (SNP) genotyping will ensure that chocolatiers know exactly what they’re getting.

Cacao Beans Credit: David Monniaux via Wikipedia

Hungry for more chocolate trivia?

Theobroma cacao may be native to Central America, but the Ivory Coast is the world’s leading cocoa producer yielding more than 1.6 million tons annually. West Africa dominates cocoa production for the world.

Valentine’s Day is a popular day for chocolate and the highest single day for chocolate sales is February 13^th. We purchase around 60 million pounds of chocolate worth about $350 million in the days surrounding Valentine’s Day. This includes about 36 million heart-shaped boxes filled with chocolate candies. Impressive to be sure, but Easter and Halloween still trump V-Day for holiday sales of chocolate.

Each American eats about 10 – 12 pounds of chocolate every year. We may be accused of many excesses compared to the rest of the world, but we are not superlative at chocolate consumption. The world leader- the Swiss consume an average of 21 pounds of chocolate annually.

If you still need more Valentine’s Day plant science, check out yesterday’s post Roses are red or the V-Day edition of Plants in Pop Culture by Postdoc Street or Say it with flowers by Malcolm Campbell. If you’re more in the mood for scary and unsettling chocolate-related news, read Ed Yong’s Ant farm from Aeon magazine. OK, that’s enough reading. For crying out loud, go tell someone you love them (with plants).

Johnna

*Thankfully, the ancient Olmecs were gustatory adventurers and developed a way to enjoy the chocolate flavor. Needless to say, Columbus liked the drink and there was no keeping it a secret from Europe. Check out the links below for more on the fascinating history of chocolate.

References and Links:

http://www.thestoryofchocolate.com/

http://www.kew.org/plants-fungi/Theobroma-cacao.htm

http://www.icco.org/about-cocoa/growing-cocoa.html

http://en.wikipedia.org/wiki/Cocoa_bean

http://en.wikipedia.org/wiki/Theobroma_cacao

http://www.xocoatl.org/variety.htm

http://news.sciencemag.org/biology/2014/01/scienceshot-genetic-test-high-quality-chocolate

http://www.delish.com/food/recalls-reviews/facts-about-chocolate

http://www.tinyprints.com/interesting-chocolate-statistics.htm

http://www.cnn.com/2013/02/13/living/valentines-day-statistics-btn/

http://www.statisticbrain.com/valentines-day-statistics/

http://candy.about.com/od/thecandyindustry/a/vday_trivia.htm

http://www.zchocolat.com/en/the_history_of_chocolate.asp

http://www.bostonhistory.org/sub/bakerschocolate/choc_industry.html

http://news.sciencemag.org/biology/2014/01/scienceshot-genetic-test-high-quality-chocolate

http://pubs.acs.org/doi/abs/10.1021/jf404402v