Hello! I'm Veronica. I'll Be Your Nectar Guide Today

The plant below is called Veronica.  That's its scientific name and its common name.  In our outdoor classroom, it's located on the rocks behind the pond, and it's blooming like crazy right now.  Veronica flowers have something really neat called nectar guides. 

Nectar Guides on Veronica Flowers

Nectar guides help bees find flowers.  They point to the part of the flower that contains the nectar, which is what bees are looking for.  Nectar is sugary plant sap found in the base of many flowers, and it is perfect bee food.  I like to think of nectar guides working a lot like the stripes and lights on airport runways telling airplane pilots where to land their planes.

Why would flowers advertise where their nectar is?  It turns out flowers are offering the nectar in a bargain.  Do you see those tiny white structures poking out of the flowers in the picture above?  Those are anthers, and they contain a dust called pollen.  Flowers must have pollen moved from one flower to another in order to be able to grow seeds to grow a new generation.  While a bee sips the nectar in a flower, those anthers are in the perfect place to dab some powdery pollen onto the bee.  Then the bee rubs off the pollen at the next flower it goes to.  The flowers are giving the bees a meal in return for moving their pollen from one place to another.  (Do you remember the name for a close relationship between two organisms where both organisms benefit?  The answer is at the bottom of this page.)

Bee-pollinated flowers usually have nectar guides.  Flowers that are small, fragrant and with a shallow cup for nectar are usually bee-pollinated, and we have lots of bee-pollinated plants at our outdoor classroom to discover.  You may not always notice nectar guides on bee flowers because sometimes the guides are invisible to human eyes.  Strangely enough, there are more colors of light than humans can see.  Rainbows actually have more stripes than humans see, in colors we haven't imagined.  Bees can probably see one more stripe on the rainbow than we can.  We call this color ultraviolet, and know it exists because we can detect ultraviolet with machines.  But how do we know bees can see ultraviolet?  Because scientists have given bees eye tests!  Scientists tested bees' eyesight by making fake flowers.  On some flowers, they painted nectar guides with an ultraviolet dye.  When you offer fake flowers to bees, the bees are way more curious about the ones with the ultraviolet nectar guides than the ones without nectar guides.  Scientists have detected ultraviolet nectar guides on real flowers (sunflowers have ultraviolet nectar guides).

Go back to the picture above and see if you can find the nectar thief.  A nectar thief is something that steals nectar without moving pollen - a parasite!  The nectar thief on our Veronica flowers is an ant toward the left of the picture.  As we learned last week, ants eat sugar, so it's no surprise that they would like flower nectar.  The ants are too small for the anthers to dust them with pollen, so they slip in, drink the nectar and slip out again without helping the plant.  Ants mostly use smell and taste to find their way in the world, so they probably don't even notice the nectar guides.  If you are jealous of bees for seeing one more color than we do, then you're really going to be mad at ants.  Scientists think ants can smell and taste an enormous number of things humans can't, with much more precision.  If you don't believe me, try closing your eyes and finding your way around using just your nose and tongue, and you will appreciate just how much better ants' senses are.

Answer: Mutualism

Why Do Sunflowers Follow the Sun?

Blooming sunflower.

It feels good to look at, doesn't it?  Something about bright yellow and radial symmetry is so pleasing to the eyes and mind.  Perhaps the visual buzz we get from gazing on sunflowers is due to the arrangement of the flower parts in what is known as Fibbonaci spirals, which I will not attempt to explain to you, but which you can learn about here in a fascinating animation.  No matter how much you understand Fibbonaci spirals, sunflowers are captivating.

The top picture shows a recently-opened sunflower inflorescence, or group of flowers.  Each dot in the face of the sunflower is actually a single flower, and the picture above shows sunflowers at the stage of pollination.  After pollen has been transported from the male parts of the flower to the female parts of the flower, the female parts of the flower begin to grow into what we know of as sunflower seeds.  In the two photographs below, you can see a mature sunflower inflorescence transitioning to sunflower seeds.

Sunflower finishing blooming and turning to seed.

Sunflower seeds not yet turned black arranged in a Fibbonaci spiral, allowing for maximum packing of seeds.

Above, you can see whitish green sunflower seeds packed together with their pointy end in.   The Fibbonaci spiral arrangement allows the plant to pack as many seeds as possible into the space available.  As this sunflower matures, the seeds will turn striped white and black like what we're accustomed to seeing in the grocery store or birdfeeder.  For a more detailed description of sunflower floral structures, see my older post on aster-type flowers, written when I wrote catchier though less-internet-searchable titles for my posts.

Sunflowers also do that amazing sun-following trick that makes these plants seem to possess some mystical powers.  Well, if you'd like to maintain your sunflower mysticism, I suggest you skip the rest of the text in this post and just look at the pretty pictures.

Sunflowers facing the sun.

What's really going on here is something called heliotropism, and lots of plants do it.  Heliotropism means moving toward the sun.  If you've ever repositioned yourself periodically during an afternoon of misguided youthful tanning in order to get even sun exposure on all parts of your previously cancer-free skin, you've done heliotropism yourself.  The puzzle with sunflowers is, why do the flowers need to face the sun?  To even out tan lines? To look good in a white dress?  To appear thinner?  To fit in with their friends?  Read on.

The truth is, the stems of all actively growing sunflower parts - flowers and leaves - grow to face the sun in order to maximize photosynthesis.  During the day, the stems elongate on the side away from the sun, tilting leaves and immature flowers toward the sun throughout the day and ending up facing west at sunset.  When there's no light (so...night time), the other side of the stem grows, pushing the leaves and flowers back to the east where they will be facing the sun at sunrise.  Growing leaves and immature flowers are green and actively photosynthesizing, and heliotropism provides them with 10-15% more sunlight than just sitting still.

Take a look at the picture below.  On the right, you can see an immature sunflower inflorescence covered in green bracts, which are obviously photosynthesizing since they are filled with chlorophyll and appear green.  The younger sunflower has immature leaves held up and facing the sun as well.  The lower leaves on the younger sunflower, as well as all parts on the older sunflower, have matured, and though they are generally facing up, they are not facing the sun.  The older sunflower is drooping from the weight of the developing seeds.

Young sunflower parts following the sun, old sunflower parts stuck in place.

So just-opened sunflowers like the gorgeous ones in the vase below (if they weren't cut off from their stalks) are still growing some, so they still face the sun.  As soon as they mature, they usually end up facing east and staying there.

Bouquet of sunflowers

Three Sisters Molé Enchiladas with Blackberry Salsa

This is a special cooking edition of my blog.  Don't panic - cooking is nothing more than applied Biology (and Chemistry and Physics and Math and Art...), so there are some way interesting biological phenomena to write about here.  One of my cooking heroes, Isa Chandra Moskowitz, has issued a cooking challenge, and I took the bait.  Isa Chandra is the author of several vegan cookbooks, including Appetite for Reduction, the most useful and well-thought-out cookbook I've ever used.  The challenge is to cook a vegan entrée in under 40 minutes using black-eyed peas, bittersweet chocolate, mint and blackberries.  The recipe must be published on the internet, and there are prizes and fame/fortune involved.  I'll report back about the results of the contest!

Here is a picture of my invention, Three Sisters Molé Enchiladas with Blackberry Salsa: 

Three Sisters Molé Enchiladas with Blackberry Salsa

The contest ingredients got me thinking about agricultural centers of origin.  Agriculture started in many concentrated locations (centers of origin) throughout the world, and cuisines arose based on what crops were domesticated from the species growing in the area, with foreign ingredients added in to the extent that cultures traveled and mixed.  See if you can match the crops with the center of origin here based on what you know about modern international cuisines.  Answers are below the table.

Center of Origin	Crop
1. China	a. wheat, oats, fig, pomegranate
2. India	b. maize, beans, tomato, potato, pumpkins
3. Ethiopia	c. wheat, barley, sorghum, okra, coffee
4. South America	d. wheat, rape (canola), peas, lettuce, asparagus
5. Mediterranean	e. rice, chickpea, eggplant, tangerine
6. Middle East	f. millet, soybean, cabbage, radish, apple

Answers: 1f, 2e, 3c, 4b, 5d, 6a

Since two of the challenge ingredients (chocolate and blackberries) originate from the New World, and beans are mostly a New World crop (though black eyed peas originated in Africa), I decided to mine this vein and emphasize New World crops.  I ended up with enchiladas based on the agricultural icons, the three sisters: beans, corn and squash.  I also used tomatoes, peppers, onions, blackberries, chocolate and sunflower seeds in the recipe.  If only I could have figured out how to add cranberries, potatoes and sweet potatoes, I would have hit all the biggest crops to have originated from the New World.  Ingredients from elsewhere in the world include cumin, cilantro, oregano, wheat, cucumbers and lemon.  Isn't it strange that cumin, cilantro and cucumbers, ingredients that are indispensable to Tex-Mex cuisine, were imported to the Americas?  And that tomatoes were not an original part of Italian cuisine but were brought to Europe from Central America? 

So who are these sisters, and what are they doing in a vegan recipe?  The three sisters are staple crops grown together as companion plants by several groups of Native Americans.  The seeds of beans, corn and squash are planted in a group on a mound.  The corn grows tall and straight, providing both food for people and a pole for the beans to climb.  The squash stays low to the ground and keeps the soil cooler and moist by shading it around the base of all three plants.  It also has prickly leaves, deterring some potential pests.  The beans stalks climb the corn, lifting their fruits off the ground and taking advantage of light above the squash leaves.  At the same time, the bean roots enrich the soil with nitrogen for all three plants.  The three sisters produce more food when grown together than any of the plants grown separately.  In addition, the beans and corn provide complete protein from vegetarian sources for their human cultivators.

The recipe is below, if you'd like to make this meal-with-a-story.  It turned out to be delicious, and it's a low-calorie and low-fat meal as well.  The first time you make these, you'll need to be a Zen kitchen master to get everything done in less than 40 minutes: banish the pets and kids, turn off the radio, stand up straight, elbows in, breathe into your abdomen.  You can do it.  It's quick and easy the second time through, since all the components are actually very simple once you know how they go.  I've found this to be the case with any new recipe I make - there's always a learning curve.  You can also prepare the salsa a day ahead and let it sit in the fridge to develop its flavors, but that would violate the 40 minutes thing.

Three Sisters Molé Enchiladas with Blackberry Salsa

Three Sisters Molé Enchiladas with Blackberry Salsa
* Ingredients with asterisks evolved and were domesticated in the New World
Serves 6, at approximately 450 calories per serving, depending on your corn tortillas

Molé Enchilada Sauce Ingredients
1 T sunflower oil*
1 T whole wheat flour
2 T chili powder*
1 t cumin
2 c vegetable broth
1 small can tomato paste*
2 t fresh oregano, minced (1 t dried)
2 oz vegan bittersweet chocolate*
1/2 t salt


Enchilada Ingredients
1 t sunflower oil*
1 large onion, chopped (reserve 2 T for salsa)*
1 medium zucchini, chopped*
2 cloves garlic, minced
1 jalepeno, diced*
1 t cumin
1 15 oz. can black eyed peas, drained and rinsed (*most beans originate from South America, but not black eyed peas)
1 15 oz can hominy, drained and rinsed* (you could substitute sweet corn if you prefer, but add it with the zucchini while cooking)
12 soft corn tortillas
2 T roasted, salted, shelled sunflower seeds*

Salsa Ingredients
2 T chopped onion (from above)*
Juice of one lemon
1 t olive oil (ok, you could use sunflower, but olive oil is yummy in salsa)
2 cucumbers, chopped (peel if you like)
1/4 c chopped fresh cilantro
1/4 c chopped fresh mint
1/2 t cumin
1/4 t cayenne*
1/2 t salt
1/2 cup blackberries*

1. Preheat oven to 400 degrees Fahrenheit.

2. Make the enchilada sauce:  In a medium saucepan heat the oil on medium, add the flour and stir until toasty (30 seconds), stir in chili powder and cumin for 30 seconds, stir in broth, add all other ingredients.  Bring to a boil, reduce temperature and simmer 5 minutes, stirring often.

3. Make the enchiladas:

• In a large sauté pan on medium heat, sauté the onions in the oil until they start to soften, add the zucchini, garlic, jalepeno and cumin and continue to sauté until the zucchini starts to soften.  Stir in the black eyed peas and hominy and allow to heat up. 
• Dunk the tortillas in the enchilada sauce and wrap a large spoonful of filling in each tortilla.  Careful - everything should be hot at this point - don't burn yourself.  Line up the tortillas in a large glass baking dish.  Pour the enchilada sauce over the enchiladas and sprinkle sunflower seeds on the top.  
• Bake for 10-15 minutes uncovered, until the edges of the tortillas start to brown and the sauce is bubbling.

4. Make the salsa while the enchiladas bake: Combine all ingredients except blackberries in a dish and stir well.  Gently stir in the blackberries.

5. Serve enchiladas topped with a spoonful of salsa.



I owe a big thanks to my friend, Jenny, a vegan food aficionado, for the idea to make enchiladas.  Thanks also to my friends for being guinea pigs: Bruce, Coke and Linda, your bravery and enthusiasm are inspiring!

They're altogether compound, the Aster Family

Behold, a giant sunflower, the best-known and most beautiful member of the Asteraceae, or aster family.  The Asteraceae is a huge family with many important members, and it is considered one of the most complex and highly specialized plant families.  The structure of aster-type plants is very different than the basic plant structure, which means it has changed a lot from its evolutionary ancestors.  The Orchid family (Orchidaceae) is also considered highly specialized, and it is an equally large and important plant family. 

Sunflower

The sunflower variety seen here has been bred to produce amazing quantities of  sunflower seeds, but it will serve as my example for how this plant family works.  All members of the Asteraceae have flower heads that are actually clumps of tiny flowers.  If you look closely at the sunflower head above, you will see that is is composed of hundred of tiny yellow and brown structures.  Each of these is a separate flower with its own miniature petals and male and female reproductive structures.  The main flowers in the sunflower are disk-type flowers.  These disk flowers are found in the center of Asteraceae flower heads.  When you look closely at the petals at the edge of the sunflower head, you can follow each one in to see that it is the single petal for a small flower on the edge of the sunflower head.  Flowers with a single large petal are called ray flowers.  Next time you encounter an aster-type flower, tear it apart to observe how it's put together.  You'll easily see how the miniature flowers are clumped together.

Some members of the Asteraceae have only ray flowers, like dandelions and chicory.  Others have only disk flowers, like thistle and ageratum.  Most composits, as members of the Asteraceae are also called, have both disk and ray flowers, like daisies, rudbeckias and zinnias.  Often ray flowers are infertile, meaning they don't actually produce seeds.  On the sunflower above, the disk flowers will each mature into sunflower seeds, but the ray flowers will just fall off.  Their job is finished after they have attracted bees to the newly-opened flower head.  Disk flowers are inconspicuous and do not attract bees very well, even though they produce seeds.

In zinnias, the ray flowers mature first, which you can see in the picture below.  You might just call the ray flowers petals, if you didn't already know better.  Disk flowers mature as the flowers age.  They look like yellow mini-flowers in the center of the main flower. 

Zinnia

Below is a row of rudbeckias, also known as Mexican hat flowers.  Rudbeckias, like most aster-type flowers are great at attracting pollinators like bees, butterflies and other insects.  The pollinators they attract also pollinate other plants nearby, like the tomatoes in the next row.  Many of the pollinators are also predatory insects that help to eat harmful insects.  These flowers are an important farm crop, but they also help keep the farm working smoothly and make it look gorgeous.

Rudbeckia

 I couldn't resist including this last picture.  I spent my first hour on the farm today harvesting zinnias and sunflowers, my two favorite flowers.  It was a special delight to walk among the 7-foot-tall sunflowers as they faced the morning sun.  The bees were just getting started working for the day, and their buzzing grew louder by the minute.  By the time I was finishing, I had to wave bees off of the flowers as I cut them down.  They were surprisingly patient with me, just moving on as their flowers fell beneath them.  As I finished the task, I carried away sunflowers by the armful for some very lucky farm customers.

Sunflowers facing the sun