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

Hey Buds!

Today felt like winter, but if you read nature instead of reading the thermometer, spring is already here.  Tree buds are among the first things to reveal that winter is over, and many of the buds at our outdoor classroom are already saying spring.  Twigs are the ends of tree or shrub branches, and the caps at the end of twigs are called buds.  Buds are the most exciting things about twigs (and trust me, there are a lot of exciting things about twigs).

Buckeye twig with three buds.  The end bud is starting to open.

Generally, ends of plant parts are very important, because these parts contain the only plant structures that can make new growth.  Parts capable of plant growth are called meristems.  Look at the end of a tree’s twig and you will see a structure called a bud.  Each bud contains a meristem covered with tiny leaf-like things called bud scales.  Scales are the protectors that keep the meristem inside from dying in the freezing cold of winter.  This time of year, the meristem starts to grow, and it pushes the scales aside.  As the meristem grows, it starts to produce either new leaves, stems and twigs or new flowers.   If you’re curious, cut off a swollen bud, slice it in half from top to bottom, and look at the cut surface with a magnifying glass.  You’ll see sliced immature leaves or flower petals.

Large buckeye bud just starting to open.  Notice the bud pushing the bud scales aside.

Plants grow very differently than people do.  People get longer and wider in every area of their bodies as they grow from child to adult.  So your arm in first grade will be both shorter and thinner in all sections, upper and lower arm, hand and fingers, than your arm in the twelfth grade.  Most plants only grow longer at their tips. (Can you guess what plants don’t grow from their tips?)*  Imagine if your body only grew longer at the ends of your toes and fingers – your adult body would look VERY different.  Plants’ stems (including tree trunks) and roots can grow wider at any point, which is why it takes more people to hug around old trees than young trees, but they only grow longer at the tips.  People often think that if they were to carve something into a tree and come back in 20 years, the carving would be very high off the ground.  This is false, since trees only get taller at the ends of their branches.  [Just a reminder, please don’t carve things into trees – tree bark is the plant organ that carries food between the roots and the leaves, and damaging the bark can kill a tree.]

Back to the buds.  Look at several trees and shrubs at the outdoor classroom.  Right now many trees have some buds just starting to open and other buds in their closed-up winter stage.  It’s a great time to compare winter buds and spring buds on the same plant.  Notice the different shapes of bud scales – pointy or rounded, separate or overlapping, striped or not, green or brown.  You might also notice how some twigs become very colorful just as their buds begin to expand.

Rhododendron flower bud

My favorite thing about buds is that bud scales leave scars on the twigs when they fall off.  Bud scale scars look like tiny clustered rings around a twig.  If you look at a twig starting at the tip and move back along the twig, you will encounter several tiny rings in the same place running around the twig like tight bracelets.  Those rings are scars from where last year’s bud scales were, and everything from there to the tip is last year’s new growth!  Look further down the twig toward the main branch and you may find additional years’ of bud scale scars.  You can tell the age of a twig by counting back bands of bud scale scars from the tips to the trunk.

Rhododendron flower bud opening.

*Grass and other grass-like plants grow from meristems that are near the ground.  That’s why we can mow the grass and cut off all the leaf tips but the grass keeps growing and needs to be cut again soon.

Looking Over Clover

To any person who has spent enough time sitting on a patch of lawn to get a little bored, the leaf in the picture below will be instantly familiar. 

One clover leaf.

It's a leaf of the white clover plant, and there is plenty of it at out outdoor classroom right now.  One clover leaf has three parts, which is reflected in the Latin name of the plant: Trifolium repens.  Tri- means three, and folium means leaf.  Repens means reclining, which this plant does well, as it spends its entire life within about 3 inches of the ground.  Clover leaves usually have faint white lines in them, and they are never heart-shaped.  Another common lawn plant called oxalis has leaves divided into three heart shapes, and sometimes people get confused about it.

A patch of clover.  See any lucky ones?

White clover has several claims to fame.  First, they are tough little plants, and they survive well on lawns even under heavy foot traffic, so they grow everywhere there is a lawn.  People who are sticklers for uniform-looking lawns consider the plant a weed, but many people value the plant for its ability to grow in harsh conditions where grass can't grow.  Second, clovers are known and loved for their sweet-smelling flowers, which are white or pinkish clusters on stems.  I bet you have made a flower chain from clovers before.  Bees love the flowers even more than humans do, and they make great honey from it.  The sight of clover flowers on a lawn should serve as a warning to wear shoes, since bees are likely to be on the flowers, and stepping on a bee will get you stung.  Clover's third well-known benefit is its value as a food source for animals.  Clover seed is often included in the mix of seeds farmers plant for growing cattle forage (the plants cattle eat).

A small clover plant with leaves, stems and roots.

Clover also has a secret.  Most people don't know much about the hidden power that makes clover so important in nature and explains some of its better-known characteristics.  If you dig up a small clover plant and look at the roots, you see something that is not usually present on plant roots: tiny lumps.  Those lumps are called nodules, and they are actually little areas where clover keeps its own pet bacteria.  The clover provides food and housing (and maybe even affection) to the bacteria in return for the services the bacteria provides to the clover.  The bacteria produce an otherwise almost unobtainable nutrient called nitrogen.  Nitrogen is a nutrient used to make protein - the microscopic parts of organisms that provide much of their actual structure as well as much of the machinery to conduct life's processes.  Other plants can only get nitrogen by absorbing leftover nitrogen from dead clover-type plants or from decomposing animals or animal manure, but clover has its own constant supply.

Root nodules on a clover - where nitrogen is fixed.

Clover's source of nitrogen means it can grow on poor soil where grass can't.  It also means it has a high nitrogen content, making it more nutritious than grass for animals to eat.  When clovers die, they leave behind richer soil with more nitrogen, where other plants can now grow.

Clover is related to bean-type plants (pinto beans, Limas, black beans, lentils, peas), and all types of bean plants have the same pet bacteria for making nitrogen (actually called fixing nitrogen).  This type of interaction between two organisms that live in close contact and help each other is called mutualism.   Can you think of other examples of mutualisms?

Have you ever found a four-leaf clover?  Sometimes the plant makes an error when growing its leaves, resulting in our four-leaf symbol of good luck.  If you look at a patch of clover for long enough, you will probably find a four-leaf clover.  If you do, press it flat between pages of a book for a week or so, then you can glue it to paper or press it between clear tape to preserve it.

Japanese Quince

Every year about now I put on a few extra sweaters, check the weather forecast for snow, and go outside to look for.....flowers??!  Yes, that's right: flowers!

Japanese quince flower and flower buds.

It's time for Japanese quince shrubs to flower, and they are a welcome sight on these gray winter days.  Our outdoor classroom's Japanese quince shrubs are by the sidewalk near the entrance to the parking lot.  You can't miss them right now, as they are covered in blooms.

One of our two Japanese quince shrubs.

Japanese quince shrubs have an extremely unusual strategy for finding pollinators.  Their flowers are bee-pollinated, but there are absolutely no bees out today!  However, if you've lived in Middle Tennessee long enough, you've learned that we tend to have the odd warm day here and there throughout the winter.  When the weather warms up, beehives send out scouts to see if anything is blooming.  And for warm January days, Japanese quince have a monopoly on the blooming business, so any bees that are out will pollinate the Japanese quince.

Flower buds on a Japanese quince.

You may have already figured this out, but Japanese quinces are from Japan.  They were brought to the United States as an ornamental and edible plant centuries ago.  In the US, they are a slightly old-fashioned but well-loved garden plant.  You've already discovered their ability to brighten a dark winter day, but they also produce useful fruit, called a quince.  Quinces are relatives of apples and pears, and some types of quinces are well-loved in Asian and European cooking.  The quinces of our Japanese quince shrubs are small, hard and bitter, but they can be used to make excellent jams and jellies.  If these flowers are pollinated, we'll have some quince fruits later in the spring or early summer.  Watch out - Japanese quince shrubs have a few thorns to protect their quinces.

A sedum blooming in January.

There is another strange bloomer at the outdoor classroom right now.  It's called sedum, and it's growing right in the middle of the waterfall above the pond.  Sedums don't usually bloom until later in February or March, so I'm not sure what this little plant is up to.  But plants have variations just like people do.  Where people might have different hair colors, plants might have different blooming times.  If January turns out to be a good time for this sedum to bloom,  it will make lots of seeds and pass the early-blooming trait on to the next generation of sedums.  Next year there will be more early-bloomers.

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!

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.

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!

Bug Beds

Imagine you are an insect, and the nights are getting colder.  You don't really have a home to go to, but you need a place to snuggle in to survive the cooler nights.  There are a million places you could go.  You could hang under a leaf or sit on a tomato flower, but the real Ritz-Carlton of the insect world is the celosia flower, seen here.

Celosia

Celosias are gigantic, fuzzy, and filled with little crevices to lodge for the night.   There is even breakfast in bed for their guests, because the flowers provide plentiful nectar for bees, wasps and other insects.  I imagine it must be very pleasurable to settle in to these soft, velvety flowers.

Hive-less, or solitary bees will often nestle into or under a flower to get through the night.  If you go into your garden very early in the morning, you will undoubtedly find some sleepy bumble bees or wasps curled up inside your squash flowers or daisies.  If the morning is cool, you can even touch the bees - they will be too cold to panic. 

This week, we had an exceptionally cool day.  It was 95 degrees one day and 60 the next.  The bees and wasps (and the rest of us) were caught off guard, and they didn't leave their flowers for the entire day.  As I harvested celosias, I noticed bumble bees, cicada killer wasps, ichneumon wasps and many other wasps and bees sitting inactive amongst the celosia blooms.  I could get as close to them as I wished without disturbing them.  Unfortunately it was also raining, so I didn't get pictures.  You'll have to make do with this picture of a cart loaded with gorgeous celosias that I harvested. 

Cart of celosias

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.

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