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

Tube Flowers and Their Pollinators

Butterfly bushes (Buddleja sp.) are very well-named.  The ones in our outdoor classroom are usually surrounded by several butterflies flying from flower to flower and filling their butterfly bellies with nectar.  If you look closer, you'll notice that lots of types insects like butterfly bush nectar, and even hummingbirds have been known to drink from these flowers.  Because of the shape of butterfly bush flowers, not all nectar-feeders are able to use these plants.  All butterfly-bush-feeders must have long, thin mouthparts that fit into the flowers.  Notice the long curved proboscis on the skipper in the photo below.  The proboscis works like a silly straw, curving and extending into the base of each flower for a sip of nectar.

A skipper sipping nectar on a butterfly bush.

Below you can see one individual flower of the butterfly bush.  The green bit is the base of the flower where nectar is produced.  The purple petals form a tube that opens at the top of the flower.  The tube shape does a good job of keeping out insects that steal nectar without pollinating the flower.  Insects that can reach their mouthparts into the flower receive a dusting of pollen as they sip nectar.  When the insects move to the next flower, they drop off the pollen, allowing the flower to produce seeds.  Nectar-sippers and flowers have a trade-off where each organism benefits from the arrangement: flowers are pollinated and the pollinators get food.  This relationship is called a mutualism, and it is a type of symbiosis where two organisms benefit from the interaction.

A single tube-shaped flower of the butterfly bush.

The purple tube-shaped flowers have orange centers to help insects find their way into parts of the flower where the nectar is produced.  Most flowers have nectar guides in their centers.  Usually nectar guides are yellow or orange regions with lines pointing to the center of the flower.  Next time you are at the outdoor classroom, look for nectar guides in butterfly bush flowers and any other flowers you'll see.

Yellow/orange nectar guide inside a butterfly bush flower.

Below you can see two more organisms that are mutualists with butterfly bushes: bees and longhorn beetles.  Both pollinate the flowers and get fed in the process.  There are some insects that 'cheat' the butterfly bushes out of their pollen.  Some types of caterpillars, beetles and ants chew through the base of the flower, drink the nectar, and leave without pollinating the flower.  Look carefully at our butterfly bush flowers for some crime-scene evidence:  if you see holes chewed through the base of their tubes, you know the nectar has been stolen with no pollination payment in return!

Bumblebee and longhorn beetle working the butterfly bush flowers.

Interesting side not:  The bumblebee in the photo above was not actively feeding.  It was just holding on and resting.  This time of year, the temperatures are dropping, and insects that don't overwinter are nearing the end of their lifespan.  It could be that this bee is slowing down because it is old.  Alternately, the bee could be finding its home for the night, since I took this photo in the early evening.  Bumblebees often sleep in large flowers or near small flowers so they have a food source in the morning (wouldn't you love to sleep in a flower?).  A third possibility is that the bee is just slow because the temperature is lower.  Some bees just slow down when the temperature drops, stay in a torpor through the cold winter, and then speed back up again in the summer when it's warm.

Drinking Bees

The waterfall at our outdoor classroom attracts more than just people.  It's the ideal place for some insects to stop for a drink.  There must be a honeybee hive somewhere near the school, because our waterfall has become a bee watering hole!

Honeybee drinking water on an algae-coated rock.

Honeybees are my #1 top favorite insect, which is ironic since I was scared of them as a child.  Once I learned about them, I grew to love them best of all.  Not only do honeybees make honey to feed their offspring and feed themselves, but while they are collecting nectar to make the honey, they pollinate flowers.  Most of our agricultural crops need to be pollinated by insects, and honeybees are the best pollinators.  Honeybees are so helpful to humans that farmers often have honeybee hives on their farms to make sure their crops are pollinated.  If you like nuts, berries, apples, cherries, squash, tomatoes or avocados, thank the bees for making them possible.  I love to think of our pond as helping the bees.

Honeybees drinking on our waterfall.

We've all seen bees pollinating flowers, but I bet few of us have been able to watch honeybees drinking.  A good, clean water resource is incredibly valuable to bees, especially in the city where water is hard to find.  Bee keepers make sure their bees have access to clean water, or they provide water dishes to their bees.  Bees, like all creatures, need to drink water.  The bees use the water to make the fluids in their bodies, and they also sweat like we do to keep their bodies cool.  Bees carry water back to their hives to help keep the hives cool and to dilute the honey to feed their larvae.  Bees fan wet surfaces in their hives with their wings, causing the water to evaporate, which cools the wet surface and the hive.  You can observe this phenomenon if you dangle a wet towel in front of a fan. 

The top level of wet rocks is safest for bees to drink from.

Water is a tricky substance for small creatures like bees to deal with.  It might be strange to think about, but water is sticky to most surfaces.  In fact it's so sticky, that you have to use a towel to get it off of yourself after you shower.  The more surface something has, the more water sticks to it.  Think of how difficult it is to dry your hair, which has millions of surfaces all packed together, compared to drying your skin, which is one surface.  The stickiness of water is both helpful and dangerous to bees.

The good part about the stickiness of water for bees is that it's easy for bee mouth parts to soak up water.  Bees have a feathery tongue that sticks to water like hair does.  The bee just has to touch its tongue to water, and water wicks into it.  You can see the phenomenon of wicking if you touch the edge of a paper towel to water and watch how the water climbs further on to the paper towel.  Paper towels that are thicker with more microscopic fibers to provide more surface wick better than thin, smooth paper towels.  Bee's feathery tongues have lots of surface and are good wickers.   You can see a bee tongue sipping nectar on the flower from my garden in the picture below, but the picture is not magnified enough to tell that the tongue is feathery.

Honeybee soaking up nectar and pollinating chive flowers.  Note battered wing and pollen sack.

The dangerous part about water's stickiness is that bees' bodies can easily get stuck to open water.  If a bee lands on the surface of the pond, its body will stick and it won't be strong enough to get unstuck from the water.  The bee will likely drown unless someone scoops it out and sets it on dry land (careful - it will likely be stressed and possibly sting if you use your hand to do this).  To protect themselves, bees must stand on hard surface and drink from water that has seeped onto the surface.  Leaves and sticks on the surface of a pond are good platforms for bees to drink from.  The rocks in our waterfall are perfect surfaces from which bees can safely soak up water.

Growing Black Chickpeas

I met a fascinating plant on the farm this week - the black chickpea.  I'm accustomed to seeing tan chickpeas in the grocery store, but it turns out that chickpea skins come in the same variety of colors as human skins - light tan through yellow to red, dark brown and black.  Maybe it's because I am reading the Hunger Games trilogy (probably shouldn't have admitted that), but these plants sound like something that would be found in the arena - useful and dangerous at the same time.  You'll have to see if you agree with me - check it out:

Chickpea (Cicer arietinum) flower.

Chickpeas (Cicer arietinum) have miniature pea flowers, with the typical pea's asymmetrical petals.  The flowers each contain a tiny, elongate ovary that will elongate into a pod with seeds once the flower is pollinated.  Each pod contains one to three seeds, many fewer than English peas.  Chickpeas, regular peas and beans are all in the same plant family - the fabulous Fabaceae, or legume family.

Green chickpea pods.

The leaves and youngest green pods of chickpeas can be eaten raw.  The enlarged but green pods can be cooked like regular peas.  The mature pods turn brown and contain dry seeds. These seeds are usually eaten cooked.  The black chick peas do not turn black until they are mature and dry, and they retain their black color even after they are cooked.  Regardless of skin color, all chick peas are the same on the inside - tan. 

Chickpea pods and leaves with acid secretion making the plant glisten.

The really strange thing about chickpeas is that their leaves and pods secrete a liquid that contains a dangerous soup of acids (Katniss would know that!).  When you brush against these plants, they feel moist.  If you have any scratches on your skin, you will notice that the secretion burns painfully.  If you go blackberry picking one day then chickpea harvesting the next, you will be uncomfortable!  I imagine if you picked them all day, you might have some skin erosion.  On large farms, chick peas are harvested by machine, so don't worry too much about fingerless chickpea harvesters.  The acid is very useful to the plant.  If you were a disease organism or an insect looking to eat a garbanzo bean plant, you would definitely change your mind when you were burned by the malic, oxalic and hydrochloric acids on the plant.

Besides deterring pests, the garbanzo bean secretion does another important job.  It works just like sweat and keeps the plant cool!  The plants secrete their sweat later in their lifespan when their seeds are mature, and presumably when the growing season is edging toward summer heat.  The sweat keeps their leaves and pods cooler than non-sweating leaves when the temperature is high.  As what happens when we sweat, the plants lose water.  They are at risk of dehydrating if there is not enough soil moisture for them to absorb.  Also, moist things tend to rot or become infected as a general rule, so the acid is necessary to protect the moist plants from rotting.

Nearly dry chickpea pod.

The acid secretion on chickpea plants is both useful and harmful to people.  It tastes good, since acids taste sour.  In fact, one of chickpea's acids is malic acid, which provides the tartness in apples.  The acid secretion can be collected by draping a thin cloth over the leaves, letting it sit all night until dew forms, then wringing out the cloth.  It can be used to make a unique lemonade-type drink.  The harmful part comes from oxalic acid.  Oxalic acid interferes with the absorption of calcium and some other minerals from food, and it can aggravate kidney stones.  Oxalic acid is also found in spinach, and that's why spinach and chickpea leaves should not be eaten every single day, though moderate consumption is harmless.. 

Black Kabuli chickpea.

Above is a black garbanzo bean (chickpea) freshly picked.

So what's the verdict?  Would chickpeas make a great Hunger Games plant?  Edible but covered in burning acid - perfect!

American Chestnut Trees

Here's something you don't see every day...

American chestnut (Castanea dentata) leaves.

 ....an American Chestnut tree!  My parents are growing American Chestnuts (Castanea dentata) on their property to help bring this great American tree species back to prominence.  Mom learned about the American Chestnut and wanted to get involved, and Dad was game to help Mom put in the work needed to plant and protect these trees as they try to survive.  They are both pleased with their American Chestnuts.

Dad with an American Chestnut on Father's Day.

Eastern forests in the United States were once dominated by this tree species.   If you think about how prevalent oak trees are in the Eastern forests of this country, it gives you a sense of the size of the American Chestnut's niche.  Its nuts provided great quantities of seriously delicious food for people, deer, bears, squirrels and many other animals.  It is a fast-growing member of the oak plant family (Fagaceae), and its wood is strong and particularly resistant to decay, so it was an extremely useful lumber-producing tree.

Why am I speaking in the past tense?  Because this tree species is now mostly gone due to the chestnut blight.  Chestnut blight (Cryphonectria parasitica) is a fungal disease that evolved in Asia and was accidentally brought to the U. S. in the late 1800's, probably on furniture, lumber or nuts.  Chinese Chestnut trees evolved with the disease, so they are resistant to it, but our trees were not resistant, and they succumbed to the disease as quickly as Native Americans died from European diseases introduced by the first European settlers of this land.  The disease was discovered in 1904, and by 1950, almost all the American chestnut trees were dead, with only small shrubby root sprouts left surviving.

Chestnut catkins (flowers).  The narrow ones have only male flowers, the upper one has some pollinated female flowers, which will produce nuts.

Several organizations, including the American Chestnut Foundation, are trying to breed blight-resistant chestnuts and repopulate our forests with this missing foundation species.  Chestnut-lovers are using existing trees to search for blight resistance.  They are also breeding Chinese Chestnut trees with American chestnut trees, eliminating those that don't survive the blight, and crossing the offspring back with American Chestnuts to result in trees that are mostly American but with the Chinese blight-resistance genes.  Right now, there exist trees that are 98% American with 2% Chinese genes.  These mostly American Chestnuts are responding well to blight exposure.  Nothing against Chinese Chestnut trees - they are great, but they're adapted to Chinese ecosystems.  Chestnut-lovers and ecologists want to maintain both species - with the American Chestnut trees back in the ecosystems here.  In the mean time, many people have planted Chinese or European Chestnuts in their yards in order to have some chestnuts to eat in the fall. 

Chestnut catkins with pollinated female flowers that have become burs, and male flowers above them.

Chestnuts have either all male flowers or male and female flowers.  Mom and Dad obtained dozens of chestnuts from the American Chestnut Foundation so they would have many trees and guarantee that they could have cross-pollination between the trees.  Chestnuts cannot self-pollinate.  This time of year,  pollinated female flowers are enlarging into burs.  Burs are spiky fruits that contain chestnut seeds.  In the fall, the seeds will be mature, the fruits will crack open, and the whole bur will fall to the ground.  As soon as the burs crack open, the seeds are mature and ready to overwinter and grow into new trees or to be eaten.

There are a few remaining adult American Chestnuts in North America.  Many of the surviving ones are outside the former range for American Chestnut trees, so the blight hasn't spread easily to them.  Also, there are different climactic conditions outside our chestnut's normal range, which cause the blight fungus to be weaker, or hypovirulent.  Mom and Dad's chestnut trees are outside the normal range, so they may survive longer than other American Chestnuts.  Of the original seeds they planted, about half remain.  Their trees probably didn't die due to blight, but to non-ideal climactic conditions.  Blight tends to affect teenage trees, and these trees are younger.  It is likely that all my parents' trees will eventually die, unfortunately.  Still, they may have a resistant tree, and their trees help maintain living tissue, help educate people about the trees, and help scientists learn more about what these trees need to survive.  With so many people working to solve this ecological tragedy, it appears likely that American Chestnuts will eventually recover.  I'm so proud of my parents for helping the American Chestnut!

Parthenogenesis and the Dandelion

If you've been following along, you know that flowers are the sex organs of plants, specifically adapted to combine half of the DNA of a male plant (in pollen) with half the DNA of a female plant (in ovules) to produce a new plant, packaged in layers of a seed and wrapped in a fruit.  Sexual reproduction allows for each parent to pass on some of his/her genes to make an offspring that is combined from those genes.  It's why we all can see a little of each of our parents when we look in the mirror, and plants would too, if they used mirrors.  Unless they are dandelions.

Dandelions and Lake Michigan

Common dandelions, belonging to the species Taraxacum officinale, mostly do not reproduce sexually, though a few dandelions in Southern and Central Europe do.  The dandelions in North America are all clones of a few original European dandelions.  The method of cloning, or asexual reproduction, used by dandelions is called parthenogenesis.  In parthenogenesis, offspring are produced that look like normal offspring - starting out as embryos and growing to adults (versus asexual reproduction by fragmentation where the adult parent breaks in two, and viola, you have two new organisms).  For plants, parthenogenesis usually means producing ovules that have a complete copy of the mom plant's DNA, called apomixis.  The apomictically-produced ovules develop into seeds that are genetically identical to the mom plant, and there is no pollination involved.  That's female liberation (though there is a plant that does male apomixis!).

Dandelions decorating a lawn.

It takes a while to get used to the idea that plants have sex, but once you think about it, it makes perfect sense.  Sexual reproduction allows for continuity of traits being passed on from generation to generation along with genetic variation to survive in diverse habitats.  After you're used to 'normal' plant reproduction, parthenogenesis seems positively bizarre. Why would a plant want to give up on genetic diversity? Actually, lots of plants reproduce asexually by parthenogenesis (blackberries, onions, grasses and more), and there are some specific advantages.

The main advantage to asexual reproduction is the ability to capitalize on a successful genotype.  If humans could do this, we might have hundreds of little Steve Jobs growing up to make our future world a better place.  Instead, he left us a few offspring, but they each only have half his genes - and they may or may not have gotten the good ones.  For dandelions, their successful growth strategy can be reproduced in perpetuity because they are identical copies, with only random mutations providing genetic diversity.  Dandelions may have less need for genetic diversity, since the DNA they have allows them to grow differently depending on their growth conditions.  This is what makes them such successful and widespread weeds.

One last issue for today:  dandelions grow without being pollinated, but most dandelions do produce pollen (Did your childhood friends used to rub dandelions on your face?  Remember the yellow dust they left behind?).  Botanists scratch their heads a bit on this issue.  Dandelions that don't produce pollen can make more seeds, since they are not wasting their energy.  It may just be that because pollen production is genetically determined and dandelions don't evolve very quickly, the pollen production may just be an evolutionary leftover.  Also, there are some sexually-reproducing dandelions in the world, so if dandelions maintain the ability to pollinate potential dandelion mates, they could just happen upon a better combination of genes than the ones they already have.  I don't know that dandelions really need to become more successful at growing...though I love them, we have enough already!

Massive Pollen Overload: Hello Spring Allergies

Brace yourself.  These pictures are of terrifying plant structures that cause much anguish to their human victims, and the overall post is frankly somewhat disturbing.  Be brave.  For the first picture, imagine some ominous, slow, suspenseful music, because a threat is just beginning to emerge from its lair.  Yes, the picture below shows flowers from a wind-pollinated tree emerging out of a bud.  The tiny green globs in the picture below will open and shower the world with..........pollen!!! No!!!!  These innocent-looking little guys are going to make you miserable for the next few weeks.

Leaf and flowers emerge from this hornbeam maple tree bud.

"Can those really be flowers?" you ask. "They're so small and boring-looking." Well, not all spring flowers are beautiful and showy.  When flowers are conspicuous, you can rest assured that they are not causing your spring allergies.  Beautiful, sweet-smelling flowers are attempting to attract insect pollinators, and insect-transported pollen sticks to the flower, then to insect legs, and it does not blow in the wind.  Tiny, green, anonymous-looking tree flowers are usually wind-pollinated, which means their pollen is dusty, copious, and perfect for floating along on a breeze to any location, including your sinuses.

"Why do plants make all that pollen?  What's the purpose??!!"  You're asking a lot of questions today. Unfortunately, if you are reading this and sniffling due to a nose full of pollen, you might find my answer to be a little disconcerting.  Pollen is the plant equivalent of sperm.  So, yes, your sinuses are clogged with plant sperm.  Pollen is produced by the male parts of flowers, and it combines with the ovule in the female part of flowers to produce a fertilized cell that will develop into a new offspring plant.  In this picture, you can see the female parts of tiny winter hazel flowers reaching into the air to snag pollen grains to make some new baby hazel seeds that will grow into new hazel trees.

Winter hazel flowers with stigmas reaching out to catch wind-borne pollen.

If you were to look at grains of pollen under the microscope, they wouldn't look much like sperm.  Pollen has varied shapes, depending on the tree.  Here is a book of scanning electron microscope images of different types of pollen - amazing stuff!  My favorite is pine pollen, shaped like Mickey Mouse's head (Google it).

Pollen does a very, very, very strange thing when it fertilizes plant ovules.  When pollen lands on a female flower structure, it divides into three sperm cells, with actual flagellae.  The sperm swim down a channel in the female structure of the flower.  One sperm fertilizes the ovule, as we would expect based on what we learned about human anatomy in 7th grade.  The other two sperms combine with another cell near the ovule to make a substance called endosperm.  The endosperm is genetically the combination of two parents, but it is not really an offspring.  Endosperm is the structure inside the seed that stores food for the new growing plant.  For example, in a corn seed the endosperm is the starch in the corn kernel (yes, popcorn is exploded endosperm, and the little nubs in popcorn are toasted corn embryos....mmmmm!). Now you know why I put three "verys" in the first sentence of this paragraph.

New leaves and flowers hanging in clusters called catkins on a red oak tree.

Oak trees (pictures above and below) are my favorite trees, so don't think I'm picking on them.  They are pretty bad at making giant clouds of pollen.  Pines are even more intense.  There are a few days in spring in Georgia that you really don't want to be outside because the pine trees seem to spew pollen like snow-making machines spew snow.  If you catch a tree as it's releasing pollen and shake one of it's branches, you can make a nice, yellow cloud in the air.

When pollen lands inside your nose, the membranes in your nose recognize it as a foreign object to be removed.  Your body leaps into action with sneezes, mucus production, and swelling (which can cause headaches) in order to get rid of the pollen.  This immune response can make you tired and uncomfortable.  Fortunately trees only make pollen for a short period of time.  The benefits of having lots of trees near you (shade, habitat, aesthetics, food, property values, reduced heat bills, etc.) vastly outweigh the annoyance of allergies.  If your spring allergies are really bad, stay inside and be sure to wash your hair and clothes after you go outside to keep the pollen away from your nose.  And just wait around a few days for a spring rain shower, and the pollen will be gone.

New leaves and catkins on a white oak.

Maples in Early Spring

If you live in the temperate eastern United States, and you only know one kind of tree, it's probably going to be a maple.  Everyone knows maples.  People either recognize and love maples' unique, pointy leaves, enjoy maple syrup, admire bright fall maple trees, or played with maple helicopter seeds as kids.  Few people know what maples are up to this time of year, though.

Even without leaves, maples are very busy this time of year.  Look at the ends of the branches on this maple tree below:  there are lumps all along the branches.

Swollen maple buds ready to pop.  Early March.

Those lumps are flower buds.  Many maples flower and fruit before they leaf out.  Here is a closeup of maple flowers:

Mid March, maple flowers.

Maple flowers are pollination generalists.  Some are pollinated by insects and bees, some are wind pollinated, and some are self-pollinated.  From the tree's perspective, it pays to be flexible with pollination strategies if you bloom very early in the growing season, because it's difficult to insure that insects will be out when you're ready to bloom.  Insects are really the best pollinators.  They are great at pollinating over long distances with small amounts of pollen, but they require warmer temperatures to do their work.  Wind pollinates cheaply - you don't have to feed it nectar or a portion of your pollen to get it to carry your pollen to another flower.  But wind isn't very specific in direction, so you usually need to make a lot of pollen if you are using wind (more on this next time!).  Self pollinating is convenient, but let's face it, you don't get much genetic variety if you make kids using only your own genes. 

Either way, lots of pollination has happened, because the maples in Chicago are LOADED with maple fruit.  Notice I called these helicopter things seeds earlier in the post, and now I'm calling them fruit.  I didn't want to alarm you earlier, but here's how this works:  fruits are plant parts that hold seeds.  An apple fruit has seeds in it, and so does a cucumber, and so does a maple fruit.  The maple fruit consists of a wing and a case around the actual seed.  Open up the swollen end of the fruit, and you will find a sticky seed (and you can stick the fruit on your nose or fingers like we did when we were kids).

Maple fruits (samaras) in late March.

Maple fruits are winged, and they are adapted to being carried far away from their parent tree by the wind.  They do indeed work like helicopters - their wing catches the wind and spins them along to hopefully sunnier ground than the ground just under their parent tree (maples are indeed shade trees).  There are many types of fruits out there: berries, capsules, hesperidia, drupes, pepoes, etc.  Fruits with wings are called samaras.  Both maples and ash trees have samaras to carry their seeds away.

New (red!) maple leaves, plus some maple samaras, late March.

Above you can see some new leaves just starting to grow on this maple. I had to look hard to find maple leaves on this type of maple tree - they mostly have only fruit right now.  Below you can see two pictures of early leaf growth on a Japanese maple.  Japanese maples seem to usually leaf out before they set fruit.

Japanese maple leaf buds opened and showing the new expanding leaves, late March.

Slightly older Japanese maple leaves, late March.

Alders

I have seen so many things in Chicago that I had only previously known from reading about them: Lake Michigan, excellent public transit, Chinese steamed buns, earlobe loops that stretch all the way to the shoulders.  My second favorite (after public transit) is a tree I have always admired: the alder (here you can see the leaves, which aren't available this time of year in Chicago).

Alders are in a fine plant family, the Betulaceae, or birch family.  Birches are marvelous trees despite their small stature.  They have nicely-shaped rounded but toothed leaves, a branched and clustered growth form, and that great bark that you have to resist peeling if you don't want to kill the tree.  In fact, I like birches so well, I named my dog Birch (Botany nerd joke: his Latin name was Betula tomentosa var. lutea).

Alders have all those great characteristics except the peeling bark, but they also happen to have flowering structures that reveal an important evolutionary link.  Remember learning in 4th grade that there are two kinds of trees, evergreen and deciduous?  This distinction divides trees into the two main groups of all plants (except those weird and ancient-looking mosses, liverworts, ferns, and the fern allies).  The two main groups of plants are Angiosperms and Gymnosperms.

Angiosperms all have some type of flower, including those plants with bright, gorgeous flowers, like the tulips and those with small, dull flowers like grasses and oak trees.  Deciduous trees are Angiosperms (though a few Gymnosperms do technically lose their leaves).  Another characteristic of Angiosperms is that they produce seeds inside fruits. I'm using the botanical definition of fruit here, meaning a hard or fleshy container  around a seed, like an apple, tomato, walnut shell or pumpkin.  The term Angiosperm refers to this phenomenon of having seeds enclosed within a structure (angio = enclosed, sperm = seed).

Gymnosperms produce seeds but don't bother to wrap them in anything.  The prefix, gymno-, means naked, which kind of makes you wonder about the word gymnasium.  Gymnosperms  produce seeds in cones, but the cones do not enclose the seeds.  The naked seeds just fall right out of those cones when they are ready to germinate.  Most Gymnosperms are trees, and most of those have needle-like leaves that are evergreen and do not fall in the Fall.

I was really desperate for a picture of a cone here.  Glitter is not natural on cones.

Cones are plant organs with repeated flat things called scales. The cones are either male or female, and their scales produce either pollen (plants sperm) or ovules.  Wind blows the pollen to the ovules, and then the fertilized ovule grows into a seed.  The big cones like the ones pictured above are female cones.  Male cones look a little bit like those strange brown mini corn cobs you sometimes get in Chinese food.  The evolution of Angiosperms from Gymnosperms included the flattening and softening of the cones' scales along with production of pigments and scents.  Flowers are basically cones modified to attract insects for carrying pollen from male to female plant structures.

Alders (I haven't forgotten we're actually talking about alders here) are Angiosperms with flowers that look remarkably like cones.  The entire Betulaceae family evolved from an evolutionary bridge group of plants that maintained more ancestral gymnosperm-like characteristics in its pollen and ovule-producing structures.  So alders are modern, flowering plants that produce seeds in fruits, but they have flowers that look just like the cones from their evolutionary ancestors.

Alder flowers look just like cones!

In Which I Attempt to Fascinate You with a Minor Plant Pigment

The Amaranthaceae, or Amaranth Family, is a somewhat obscure plant family, but you'd never know it on the farm right now.  There are amaranth crops, escaped amaranth hybrids from last year, and native amaranth weeds taking over the farm this time of summer.  It's a colorful explosion of dramatic bloomers with other meek yet ubiquitous volunteers growing between the rows of actual crops.

The hoop house, a sort of open-sided green house, is bursting with ornamental cock's combs right now.  Cock's combs are in the genus Celosia, and they come in amazing colors: eye-searing red, blazing peach with yellow, glowing whitish-green and orange.  They are such shockingly bright colors due to the fact that they are fluorescent.  Fluorescent colors absorb light energy from outside the visible spectrum (like UV light) and then emit that UV light as visible light...so they do actually glow.  Fluorescence is most noticeable when visible lights are turned off and black lights are shined, but cock's combs are so fluorescent that you notice them in full sunlight.

Hoop house full of Celosias.

A Celosia close-up.  It's even brighter in real life.

Members of the Amaranthaceae and a few other closely-related plant families can fluoresce because they have an unusual class of plant pigments.  Most plants that have red parts use a plant pigment called anthocyanin.  Think maple leaves in the fall and apple skins.  The amaranths use a group of pigments called betalains for all their red and most of their yellow coloration.  Betalains are antioxidants, so they may have anti-cancer properties.  Betalains are also useful as dyes for food and cloth, but I doubt they are what make highlighter pens fluoresce. 

The fluorescence of cock's combs is useful for the plant - it attracts pollinators.  In the hoop house, the peach cock's combs were the hands-down favorite of bees and wasps.  Each plant was swarmed with pollinators large and small.  The peach sector of the hoop house was buzzing, audibly as well as visually, with insect activity.  Good thing I got over my giant ground hornet fear in the previous post. 

Peach Celosia, source.

Amaranths in the U.S. are herbs, though there are some tropical shrubs.  They have tiny flowers, usually clustered all together.  The flower parts are so tiny, they are best seen with a hand lens or dissecting microscope.  Other ornamental amaranths include Gomphrena and Iresine.  Edible amaranth, genus Amaranthus, is used as a grain.  It is an important high-protein cereal native to South America.  Weedy pigweeds, in the same genus as edible amaranth, are found here in the U. S., and though their seeds and leaves are edible, it is much more of a nuisance than a valued crop. 

On the farm, half of our interactions with amaranths involve planting and harvesting the Celosias and Gomphrenas and the other half are killing the pigweeds, spiny amaranths and escapees from last year's crops.  The escaped plants from last year are seeds that have fallen and overwintered in the soil.  They are usually crosses between different types of Celosias, so they have a blend of their parents' traits.  That means they might have unpredictable colors, small flower heads and irregular growth forms.  They don't usually make good cut flowers, and they have to be treated as regular weeds. 

An escaped and hybridized Celosia from last year's crop growing among the zinnias.

And here is your reward (or punishment, depending on your sensibilities) for reading to the end of the post:  Beets are in a closely-related plant family, the Chenopodiaceae, and their red pigment is also a type of betalain.  I have never really noticed fluorescence in beets, but I haven't tried them with a black light.  If you eat a lot of beets, you may have noticed one of the disconcerting properties of betalain.  Betalain is not readily digested by humans, and it either passes straight through the digestive tract or is absorbed into the blood and eventually filtered into the urine.  Either way, the betalains end up in the toilet bowl, the same color as when they were swallowed.

Birds Do It, Bees Do It........Even Zucchinis Do It

I am the only person in the world who seems to have trouble growing zucchini.  They are notoriously generous in fruit, and you always here gardeners joke about being overwhelmed by their zucchini crops. There are even stories about gardeners secretly dropping of baskets of zucchinis at their neighbors' houses just to get rid of them.

I've gotten better at growing zucchini plants through the years, but still have little luck with the actual fruits.  (Yes, they're fruits, according to the botanical definition.  Any plant part that contains seeds is a fruit.  Don't worry - I call them vegetables when I'm cooking.)  My home garden has a lot of shade for a garden, and my first few years of planting zucchini in the shadier regions allowed the plants to be overcome by a dusty white mildew.  Any zucchinis would wither and rot before they grew two inches.  Now my plant is in the sunniest patch I have, and it's healthy, but my zucchinis are still withering prematurely.  Here is this year's zucchini plant, recovered from the hail damage:

After talking with the farm owner where I'm working this summer, we agreed it might be a pollination problem.  Pollination is how plants reproduce, and seeds and fruits are the offspring of plant reproduction.  Pollen, is the plant equivalent of sperm, and it must reach the botanical equivalent of eggs, called ovules, for seeds and fruits to develop.  There seem to be two possible pollination problems in my case:  maybe there aren't enough bees to pollinate the flowers; or maybe there must be two plants for successful pollination.

Option 1, not having enough bees, is a distinct possibility.  There aren't many bees in my neighborhood.  I do see bumble bees, but they tend to cluster out front where all my ornamental flowers are.  I have seen no honey bees this year, which I fear is due to colony collapse disorder - see a future post on this.  To remedy this problem, I could plant some bee-attracting plants near my zucchinis so there is more of a reason for the bees to fly all the way over there.  I could also start a honeybee hive in my back yard, which I will do some day if my neighbors aren't reading this blog.  Or, I could hand-pollinate the flowers when they open every morning, which is what I have been trying.

To hand-pollinate the flowers, you must understand a little about the reproductive organs of zucchini plants.  Flowers are always reproductive organs for plants, but each type of plant is a little different.  Zucchinis and all squash-type plants produce separate male and female flowers.  Most types of plants have male and female in the same flower, but some may have entirely separate male plants with only male flowers and also female plants.  Hollies have separate genders, which is why only some hollies grow berries - only females can grow fruits and only males can produce pollen.

On zucchinis, the female flowers grow out of what looks like tiny immature zucchinis.  This organ is the female flower's ovary, and it is filled with ovules.  The ovary will one day actually become a zucchini, and the ovules will become seeds after the flower is pollinated.  Notice the thick regions behind the female flowers below - they are ovaries.

Male flowers have a normal stalk, and inside the male flowers are pollen-producing organs called anthers.  Here is a male flower:

For pollination to occur, the pollen must be transferred to sticky pads, called stigmas, inside the female flower.  Each pollen grain then produces two actual sperm cells that burrow down through the flower to an ovule and fertilize it.  Many pollen grains are needed to fertilize all those ovules inside a zucchini ovary.  When the ovules are fertilized, the fruit begins to enlarge and grow into a mature zucchini with mature seeds.  If no pollen is transferred, or only a little is transferred, there is no signal to the plant to grow the fruit, and the ovary just withers and rots like mine have been doing. 

I have been hand-pollinating for a couple of days now, by touching my finger to the anthers in the male flowers and smearing the pollen on the female flowers.  I think it may have worked!  Here you see the stigmas inside of a female flower and what I think may grow into an actual zucchini:

Regarding the second possible pollination problem, I may have to plant two zucchini plants next year.  Since I only have one zucchini plant, the pollen I used came from the same parent plant as the flower I transferred it to.  Some plants don't mind reproducing with themselves, but zucchinis may be somewhat pickier.  The zucchini that seems to be growing could have been pollinated by pollen from a neighbors plant.

On the farm, the year they had a bee hive, the squashes were much more productive, since all their flowers were being pollinated.  It really makes you appreciate the bees more when they are not there to do that garden task for us.