Prairies of the Past

The American Prairie is an iconic landscape that evokes images of rolling hills covered in wind whipped seas of grass, herds of buffalo, covered wagons and sod houses.  The Great Plains of the Midwest are synonymous with prairies, and though the Midwest has the most famous American grasslands, there is strong historical and ecological evidence that the Southeast was covered in a rich mosaic of grasslands and forests prior to European colonization.  There is an often repeated tale of a pre-contact squirrel being able to travel from the Atlantic to the Mississippi without ever touching the ground on account of the densely forested landscape. I remember hearing it as a child in the 1980’s, and it continues to spread to this day.  This idea of the all-encompassing primeval climax forest was disseminated sometime in the early 20th century.  It’s based on the relatively recent observation of forest succession occurring on open lands that are devoid of the prehistoric natural controls that keep forests in check and allow grasslands to flourish.  This assumption that all land will become forest given enough time is overly simplistic, and does not take into account the reality of the natural processes that select which plants can thrive in a given landscape.  It also ignores the numerous historical writings of early explorers that encountered large areas of naturally occurring grasslands in the Southeast during the 18th and 19th centuries.

Coastal marsh grassland

 

 

 

 

 

 

 

 

 

 

 

 

To see how the landscape has changed, let’s take a trip back through history.  One hundred and twenty two years ago in 1897, Historian Dr. John Landrum wrote:

 “Up to the breaking out of the revolutionary war, the woodlands in the upper portion of South Carolina were carpeted with grass, and the wild pea vine grew, it is said, as high as a horse’s back, while flowers of every description were seen growing all around. The forests were imposing, the trees were large and stood so wide apart that a deer or buffalo could be seen at a long distance; the grasses and the pea vines occupied the place of the young, scrubby growth of the present day.” …”It is a fact well authenticated, that in the early history of the upper country there were numerous prairies covered only with the grasses and the pea vine, but which have since been covered with pine, oak, and other growth.” [History, 2]

Just before the Revolutionary War, another 122 years into the past in 1775, Botanist William Bartram was exploring and collecting specimens in what is now the state of Georgia.  In his journals, he recorded travelling through many open grasslands.  Near present day Clyo, Ga. after naming many trees and shrubs in a riverine forest he wrote:

“This ancient sublime forest is frequently intersected with extensive avenues, vistas and green lawns, opening to extensive savannas” [Travels, 309]

Near present day Sparta, Ga.:

“There is some very good land on the gradual descents of the ridges and their bottoms bordering on creeks, and very extensive grassy savannas and cane meadows always in view on one hand or the other.” [Travels, 379]

Near present day Clayton, Ga.:

“I observed growing in great abundance in these mountain meadows Sanguisorba canadensis and Heracleum maximum…..the swelling bases of the surrounding hills fronting the meadows present, for my acceptance, the fragrant red strawberry, in painted beds in many acres surface, indeed I may safely say hundreds.” [Travels, 344]

If we go another 75 years back to 1700, Explorer and naturalist John Lawson, travelling near present day Columbia, SC noted:

“we pass’d by several fair Savanna’s, very rich and dry; seeing great Copses of many Acres that bore nothing but Bushes, about the Bigness of Box-trees; which (in the Season) afford great Quantities of small Black-berries, very pleasant Fruit, and much like to our Blues, or Huckle-berries, that grow on the Heaths in England.” [Voyage, 27]

And near present day Asheboro, NC:

“We travell’d, this day, about 25 Miles, over pleasant Savanna Ground, high, and dry, having very few trees upon it, and those standing at a great distance. The Land was very good, and free from shrubs and underwood.”  [Voyage, 45]

Pine Savanna in the Coastal Plain

These historical descriptions use words like savannas, prairies, meadows, and cane breaks, but they are all talking about grasslands.  Grasslands encompass a spectrum of landscapes that share the common defining characteristic of a ground layer of vegetation dominated by grasses and other graminoids (such as sedges, rushes, or canes).  Types of grasslands include: savannas, balds, dunes, glades, meadows, marshes, barrens, bogs, fens, and even some woodlands as long as the tree canopy is sparse and grasses are the dominant type of vegetation.  (Thanks to Southeastern Grasslands Initiative for the definition and types). Historical descriptions and land surveys give us an idea of what the landscape looked like in precolonial days and grasslands were very much a part of it.  Since then, the absence of fire and large herds of grazing animals have contributed to the decline of grasslands and allowed successional forests to creep into areas where they previously could not have survived.

Large herds of animals were one of the first casualties of colonial settlement.  Furs were a major means of barter for many settlers, and game was abundant.  Historian Dr. David Ramsay wrote in 1858: 

“In the year 1750 when the settlement of the upper country [of South Carolina] began, there were so many buffalos, which have long since disappeared, that three or four men with their dogs could kill from ten to twenty in a day.”…”The waters abounded with beavers, otters and muskrats. Twenty beavers have been caught by one man in one season on Fairforest.” [History, 305]

 Bison and beavers are both major controls to the spread of woody plants.   Bison graze on grasses, but unlike domestic cattle they can also digest cellulose, so they will eat entire tree seedlings and the bark off of larger trees all the way around the trunk, which will cause the trees to die. Herds of bison churn large swaths ground as they graze and seasonally migrate and fast growing grasses are the first to colonize their wake.  Beavers not only prevent the spread of trees, but actively reduce their range by felling them and flooding large areas so the soils are too wet for trees to survive.  The edges of a beaver pond are ideal habitat for many grasses and forbs.   After a dam is abandoned and breaks down, the large open area that was behind it with newly enriched soils often becomes a meadow.  The pelts of bison and beavers were major exports from the colonies to Europe and their drastic reduction in numbers or outright removal from the Southern landscape had far reaching effects on the plant communities adapted to open, disturbed areas.

Broom Sedge (Andropogon virginicus) just waiting to burn.

 

 

 

 

 

 

 

 

 

 

Fire is the other main check to forest succession that was slowly removed from the landscape as it was settled by more and more people.   Fire is a naturally occurring phenomenon that has affected plant growth, survival, and adaptation as much as soil pH, precipitation, and faunal predation.  The climate of the southeast with frequent thunderstorms and some of the highest occurrence of lightning strikes per square mile in the world ensures that fire will enter the landscape sooner or later.  While the Native Americans were known to have set fires to clear land and to flush game they were simply facilitating a natural process that had been occurring for millennia. Native Americans were not the creators of grasslands or other fire dependent ecosystems, even if their actions may have helped them thrive and expand in the centuries prior to European contact.  Frequent fires became less common through the 18th and 19th centuries.  After the Civil War many Northerners bought Southern lands and brought their ideas of fire suppression from the urbanized areas and fire sensitive forests of the Northeast down South. Federal and State owned lands were focused almost solely on timber production and fires were all but excluded from the landscape.  Trees that aren’t adapted to cope with fire will quickly take over an open sunny area if fire and other controls are removed from the equation.  This process of forest succession is what led many scientists to believe that forest is the climax habitat of the southeast and led to the creation of the myth of the travelling squirrel.  The very idea of naturally occurring Southern grasslands slowly faded into obscurity.

Prairie restoration area at Panola Mountain State Park

In summary, there once were prairies and other grasslands all over the South, but they have almost disappeared due to habitat loss and lack of forest controls.  Not all is lost, however, as small pockets of grassland survived in highway right of ways, pastureland, power line corridors, and other areas where  people controlled the spread of trees and shrubs with mowing or grazing animals. In the latter half of the 20th century, prescribed burns were recognized as necessary for the creation of habitat for quail and other game animals and fire was slowly reintroduced to the landscape. Further studies have documented the numerous plants and animals that benefit from prescribed fire and led to its widespread acceptance as a tool for conservation.  Today, numerous organizations and land managers are working to rehab, restore, and even create new grasslands.  We will be profiling a few of these projects and land managers in upcoming posts, so check back for more information about Piedmont Prairies and the plants that call them home.

Prairie restoration planting in a power line cut at CRNRA.

 

 

 

 

 

 

 

 

 

 

Works Consulted

 

Works Cited

Exactly.


Fruits of Millennia Past

You’ve most likely seen the insides of a pumpkin one way or another in the past month.  It’s a stringy, gooey mess full of seeds surrounded by thick fleshy walls.  Have you ever stopped to consider why it’s structured that way?  How are those seeds going to get out of that gourd and into a place where they can germinate into baby pumpkin vines?  These days humans cultivate and eat pumpkins, planting their seeds year after year for the past several thousand years.   However, the ancestors of today’s pumpkins were growing wild 30 million years ago in a landscape devoid of humans in what is now North and Central America.

Two ways humans use pumpkins.

  Ancestral pumpkins were smaller than modern ones, but still softball sized, and were full of bitter, toxic compounds to deter potential seed predators.  These gourds were adapted to be eaten whole, with minimal chewing, so as to avoid crushing the seeds.  What animal has the appropriately large teeth and esophagus to handle such a task and the body mass to tolerate toxic compounds?  Did you guess a five ton ground sloth? How about a Gomphothere or their more familiar cousin the Mastodon? Maybe a 12 foot tall camel? If you guessed any of the above you are probably a Paleontologist, and most likely correct.  There were dozens of species of megafauna populating the American continent for millions of years and they co-evolved with many of the plant species (or their ancestors) that are still here today.

 Plants have been growing on land for nearly half a billion years.  In that time countless growth and reproductive strategies have been attempted.  Most people are familiar with the pollination process: male flower parts produce pollen grains that need to be transferred to the receptive female ovary, and the resulting genetic combination is encapsulated in a seed.  Pollination as a means of reproduction wasn’t always an option.  Spores were the dominant means of reproduction in plants for the first several hundred million years after they colonized land.  This strategy is so successful that many plants, such as ferns and mosses, still use spores to reproduce to this day.  A major limiting factor of this strategy is that it requires a moist or wet environment for the spores to combine their genes and sprout a new individual. 

The development of pollen and seed about 380 million years ago allowed plants to move into drier areas and expand their potential range immensely.  Another 250 million years later saw the rise of flowering plants that encased the seed(s) in a fruit.  Fruits are a major part of why flowering plants (Angiosperms) are now the most diverse and wide-ranging branch of the plant family tree.  By protecting their seeds and exploiting animals’ need for calories plants gained the ability to move long distances to new areas and free fertilizer. Fruits and animals have been in a co-evolutionary tango ever since that has shaped the habits of both.

Hawthorn (Crataegus uniflora) fruits on thorny branches.

 In the past 100 million years that flowering plants have been producing fruits lots of animal species have evolved, thrived for millions of years, and then gone extinct.  What happens when the agent of dispersal that loves to eat fruits and unwittingly transport and deposit seeds in far off places suddenly (geologically speaking) disappears?  Fruits will rot on the vine or on the ground and seeds will fall victim to fungal attack, rodent seed eaters, or be forced to try and grow in the shade of their parent.  A new dispersal mechanism must be found or plant populations will become isolated, inbred, and slowly wink out of existence.  This is the situation a number of North American native plants found themselves in recently.  The Pleistocene megafauna that roamed the continent for millions of years went extinct between 15,000 and 8000 years ago.  Fruits that were meant to appeal to these giant mammals still hang on trees today waiting for a ride that will never arrive.

Honey Locust (Gleditsia triacanthos) seed pod that was still on the tree from last year. (6 in. scale)

Plants that appeal to and/or defend against extinct animals are said to be ‘anachronisms,’ that is “belonging to a period other than that in which it exists.”  A few examples of plants with anachronistic fruits in the Southeast are Honey Locust (Gleditsia triacanthos), Paw Paw (Asimina triloba), Persimmon (Diospyros virginiana), and Kentucky Coffee Tree (Gymnocladus dioicus).  Beyond the Southeast, other familiar new world fruits such as Papaya, Avocado, Guava, Passionfruit, and Mesquite pods were originally adapted to appeal to beasts much larger than humans that could swallow the rind, pulp and seeds together in one or a few bites.  One can also see anachronisms in the thorny defenses on plants such as Hawthorns (Crataegus spp.), Honey Locust (Gleditsia triacanthos), Devil’s Walking Stick (Aralia spinosa), and Yucca (Yucca spp.).  These thorns are meant to discourage leaf browsing, but are larger than necessary, and continue up the stems well above the height needed to discourage any living herbivores. 

Serious defense on the Honey Locust (Gleditsia triacanthos).

 

The arrival of humans in the Americas (14,000 to 40,000 years ago, depending on who you ask) coincides with the extinction of the majority of the large seed dispersers, and may have been a contributing factor.  So it goes. It just so happened that many of the fruits and seeds here also appealed to the humans’ mammal palette, or they found inventive ways to neutralize toxins and make them edible and nutritious.  This new avenue of dispersal allowed many plants to continue to spread and thrive even as they produced fruits that were originally meant for someone else.   

The next time you see an avocado, butternut squash, papaya, or if you’re lucky enough to get a pawpaw, think about who it originally appealed to in a world without ovens or knives.  Millions of years ago when humans and chimpanzees were just diverging from a common ancestor in Africa, giant camels, sloths, rhinos, mastodons, and other beasts roamed the North American continent plucking persimmons, pawpaws and locust pods from the trees.   These giants feasted on prickly pear fruits and desert gourds during their seasonal migrations and they consistently deposited the seeds in a pile of fertilizer further down the trail.  Plants are still using their tried and true methods that worked for millions of years, so the brief absence of their partners for 15,000 years has not yet sunk into permanence.  In the meantime they’ve found us human types that are all too happy to pamper their descendants and spread them far and wide if they happen to also appeal to our senses.  Bon Appetit!

Immature Pawpaw fruit in July

 

Credits, References:

The inspiration for this post, and from which I drew heavily for information, is the book “The Ghosts of Evolution: Nonsensical Fruit, Missing Partners and Other Ecological Anachronisms” by Connie Barlow (2001). It’s a great read, and very accessible even if you know nothing of Paleontology, Botany, or Ecology.  She weaves the story of two of the progenitors of the concept of Evolutionary Anachronisms, Dan Jantzen and Paul Martin, with her own investigations into the edibility of fruits, the natural history of plant species, and interviews with botanists, paleontologists, and ranchers. She thoroughly examines past hypotheses of seed dispersal syndromes and shows how many plants have found alternative vehicles (humans and otherwise) to survive.

The wikipedia page for “Pleistocene megafauna” is also a great summary and jumping off point if you click through the references at the bottom to learn more about the giants that took the place of dinosaurs.  


Spiders in the Garden

Editor’s Note: While this was posted by Jeff, it was written by Clair, the newest member of the BHF team.  She has been working hard to improve our propagation beds and in the process was inspired to write this appreciation of Arachnids. Enjoy!

Green Lynx Spider (Peucetia viridans) with a captured wasp

If you have been outside at all lately, whether walking through the woods, spending time in your garden, or even just sitting on the porch, chances are you’ve come in contact with a spider, or at least its web.  Most spiders have gotten a bad rap over the years as something to fear. Movies, Halloween decorations, pest control advertising, and the spiders’ skittish behavior play into these fears. While most spiders are venomous, very few have the jaw-power or enough venom to do any real harm to a human.  The brown recluse and the black widow are exceptions, but chances are slim you will come across these in your garden (Even if they did manage to bite you the chances of it being fatal are basically zero). Remember, you are much larger than a spider and they are more interested in getting away from you than biting you.

You may be thinking, ‘well, even if the spider won’t harm me, they eat everything, including the pollinators, so why have them around?’  True, spiders are not picky eaters and will eat the “good bugs” along with the “bad.” Spiders may be the most beneficial predator in your garden and play a huge role in controlling pests.  They are not selective in the insects they eat, so it is guaranteed that they will occasionally snag a bee or butterfly in their web, but the few beneficials they do kill is no match for the natural pest control they provide (free of charge, I might add!).    Spiders will feast on aphids, armyworms, leafhoppers, flea-hoppers, leafminers and spider mites. They attack the spruce budworm, pine sawfly, sorghum midge and tobacco budworm. They especially like caterpillars, thrips, plant bugs, cucumber beetles, scarabs and flies. Larger spiders eat larger prey, so some will even eat wasps, cicadas, and grasshoppers.  If you’re really lucky, you may even get to see a spider and a praying mantis battle it out.

There are two types of spiders that you are likely to come across in your garden: web spinners, or orb weavers, and hunters.  Garden spiders and crab spiders are very common web spinners in Georgia. They spin their webs between plant stalks, tree branches, or even from tree branch to ground.  Spiders usually hang out in the middle of their web and wait for an unsuspecting insect to fly into the nearly invisible trap. Garden spiders are often large, like the yellow and black orb weaver or the green garden spider, so hopefully you will catch a glimpse of them before accidentally walking straight through their web.  However, they sometimes hide in a protected corner and wait for their prey from a safe spot. Crab spiders tend to be small and crouch in the center of the web with their eight legs pulled under their armored shell, making them harder to detect as you approach their web.    

Black and Yellow Garden Spider (Argiope aurantia) on its nearly invisible web.

Wolf spiders are a common hunting spider and do not spin traditional webs.  They are most likely to be found on the ground, nesting in mulch, ground covers and old wood piles.  If you have tall grass in or near your garden you may be lucky enough to attract a funnel spider. The aptly named funnel spider creates a dense funnel with their silk and waits safely in the back for prey to wander onto the outer funnel before they attack.  

Female spiders tend to lay eggs in the fall.  They may hatch quickly or overwinter in an egg sack before emerging in the spring.  Wolf spiders will attach the egg sack to their body and carry it with them if they feel they are in danger and need to move.  When the baby spiders emerge from the egg sack they will “balloon” by shooting a silky thread from their web spinner into the air. When it attaches to a sturdy object (leaf, branch, twig, building, etc.) they will ascend the thread and find a good place to start their first web (anyone remember “Charlotte’s Web?”).

Rabid Wolf Spider (Lycosidae rabidosa) female with egg sack attached

  To encourage spiders in your garden plant a variety of plants with varying heights, preferably plants native to Georgia. Taller plants provide a structure for orb weavers to attach their webs, and low growing ground covers create niches in which the hunters can hide.  Mulch provides a good home and helps retain moisture for wolf spiders since they do not have webs to catch the morning dew. Leave small patches of bare ground here and there for open hunting ground for the wolf spiders. Woody plants and bunch grasses make great homes for funnel spiders.  All spiders play a valuable role in your gardens’ ecosystem and should not be eradicated.  Do not feel bad if you accidentally destroy a spider’s web. They will quickly move on and begin building a new one.  Predators like spiders are a sign of a healthy ecosystem, and acknowledging the pest control services they provide is a great way to start to appreciate them as garden collaborators rather than something to be feared.


Leaf Buds: Natural Origami

This is a companion piece of sorts to my last post about leaf buds (‘Buds are Swell‘), but this is a more personal tale of a particular bud. 

It all started in January when I planted a Bigleaf Magnolia (Magnolia macrophylla) in my backyard after reclaiming an area from the abundant English Ivy that the previous owner left me.  In it’s dormant state the young tree looked like a bare branch with a pointed end sticking out of the soil.  That pointed end was a bud.

Covered in insulating hairs, the bud rode out a few snowfalls and numerous freezes until the temperatures began to rise.  Temperature dependent reactions started occurring inside the bud and it began to swell.  Cells differentiated and divided to become the specialized structures that make up a leaf.  Eventually the finite space inside the swelling bud ran out and it split open to unfold and unfurl the leaves that had formed within.

  In this particular case, those leaves that started in that tiny 2″ long bud can easily become 24″ long and 10″ wide.  Sadly, these leaves were denied that chance.  Some (literal) rat bastard chewed them right off the stem a few days after the above photo was taken.

I found it on the ground near the base of the stem.  He didn’t even eat it, probably because the leaves were too fuzzy.

        After I got over my shock and anger I decided that the least I could do is study the remains and hopefully learn something from it.  I discovered an incredibly complex arrangement of multiple leaves folded and rolled around each other inside that relatively tiny bud.  

The repeating pattern of: sheath, leaf, fold and enclose a sheath, leaf, fold and enclose…… led me to unfold and arrange 7 separate leaves for the above photo.  Even that tiniest leaf at the top is folded around an even tinier sheath that I would have needed a scalpel and tweezers to open, but I’ll bet that wasn’t even the last one in the sequence.  Thinking about how those all formed in three dimensions inside of that bud was pretty mind boggling.  ‘Natural Origami’ was my first thought and I haven’t come up with anything better.

Fortunately the tree was left with one leaf to try to feed itself.  Even if it hadn’t been left with that leaf, it had other back up plans.  As I said in my previous post about buds, they start out as just a few hundred cells, so it’s not really a big energy investment until they need to swell up into actual leaves.  Almost all plants have multiple buds somewhere other than the apical bud at the tip.  Depending on where they are located on the plant they can be called axillary or adventitious buds.  They are the multiple redundancy backup plan that springs into action when something destroys the plant’s new growth.  

As such, this axillary bud (just take a second and realize that this bud was formed at the base of this leaf inside the big bud and that each of those 7+ lost leaves had a potential bud at their base too!) and several adventitious buds that you can see below it were activated by hormones to start the dividing and swelling process all over again. 

After a few weeks of swelling, they opened to reveal a few new leafy tops for this tree.  You can see the now much larger and slightly tattered single leaf that remained on the left side of the frame.  This whole process was a setback for sure, and this tree will not put on as much new height this year as it could have, but thanks to the latent buds it is still alive and green. It was also a reminder to me that if I pause and study a plant closely I always learn something new.  

“Nature will bear the closest inspection. She invites us to lay our eye level with her smallest leaf, and take an insect view of its plain.” – Henry David Thoreau (Oct. 22, 1839)

 

 

 


Buds are Swell

Hearts a Bustin’ (Euonymous americanus) stem with numerous buds at the tip.

Deciduous woody plants have adapted to survive in the temperate regions of the world by dropping their leaves for the duration of the cold winter months.  Freezing temperatures and low light conditions aren’t conducive to photosynthesis, so trying to maintain leaves through the winter doesn’t make much sense and would probably result in a net loss of energy.  Once the temperatures do start to creep back up new growth has to begin somewhere, and that somewhere is in the buds.

Buds on a young White Oak (Quercus alba) sapling. Note the half moon shaped leaf scar just below the buds where last year’s leaf detached.

Buds are compact, often tiny, structures that are the first step toward a new leaf, branch or flower.  Where the bud is located on the plant largely determines what it will become.  Terminal, or apical, buds are at the tip of the stem.  They are usually the first to break dormancy and often impede all of the other buds on a branch or stem from sprouting until they do.  Lateral buds are farther down the stem, and axillary buds form at the joint between a branch and the main stem or trunk.

Big Leaf Magnolia (Magnolia macrophylla) bud covered in fine hairs to insulate against freezing temperatures. Big leaf, big bud

Many buds have evolved structures to protect themselves from the freezing temperatures called bud scales.  They are overlapping plate-like structures that contain a waxy substance for insulation. Others, like the Magnolia pictured above have hairs that act like animals’ fur to insulate the delicate parts inside.  Those delicate parts are cells akin to stem cells in animal embryos called ‘primordia.’  There can be as few as a couple hundred cells in a bud to start out, but as the temperatures rise and the days get longer, the cells begin to divide and differentiate into the specialized leaf parts they will ultimately become.  The first outer sign of this process beginning is when the buds swell in late winter, AKA right now in most of Georgia.  This all comes back to you, the gardener, in the fact that as the buds are swelling they need nutrients to grow!  Trees and shrubs (especially young ones) should be fertilized right as the buds begin to swell so that they have all the vital elements to make those tiny soon-to-be-leaf structures.

Blueberry (Vaccinium sp.) leaves unfurling from a newly opened bud.

Keep an eye on the buds of your woody plants over the next few weeks and you will see Spring getting ready to spring!

Serviceberry (Amelanchier canadensis) bud just starting to break open


There’s Nothing Wrong With Those Leaves, They’re Just Dying.

One of the best parts about going to plant sales and setting up a booth is that you get to hear everyone’s story about their favorite plants that you may or may not be selling.  Seeing people enthusiastic to learn and share plant knowledge refills my inner reservoir of hope.   We participated in the Hall County Master Gardener’s Fall Expo last weekend and talked to some wonderful people (many of whom were Hall Co. Master Gardeners, y’all were awesome!) and sold a bunch of plants.  One exchange in particular made me incredibly happy because I finally heard someone express the concept I’ve been trying to convey to anyone that will listen for years:  Leaves on a perennial plant (especially in fall ) are expendable and don not necessarily reflect the overall health of the plant.

Agastache leaves showing some yellowing as they break down.

I was talking to a couple as they browsed our plants, and as the wife decided she would like a Giant Hyssop (Agastache scrophularifolia) she picked up two pots and started comparing the plants in them.  She asked her husband, “Which one?” He responded that they looked about the same.  She expressed concern about the yellowing leaves on one of the plants, but it had more stems, so she kind of wanted it more. He turned to me and asked “It’s perennial, right?” I said that it was with a nod.  He said “Well, then you’re buying the roots. Those leaves are going to be gone in a few weeks anyway.”  I think I just found my new best friend.  I’m pretty sure I saw the wife roll her eyes and then select the plant with 2 stems.

Magnolia macrophylla with some leaves that have seen better days, but quite healthy roots

Leaves on a perennial plant go through an annual life cycle that eventually ends with them shutting down and dying.  This is known as ‘leaf senescence’ and most people know it more commonly as “when the leaves change color in Autumn.”  This cycle was summed up incredibly well in a paper about the molecular causes of leaf senescence that I came across:

“Leaves initiate their life as leaf primodia. During their development and growth, they become photosynthetically competent and accumulate nutrients. Leaves then enter the senescence stage, followed by their death. Leaf senescence partly involves the process of ‘wear and tear’ during aging, but mostly is a tightly regulated process with a crucial biological purpose.”    – http://jcs.biologists.org/content/126/21/4823

Leaves are formed, perform their function of collecting solar energy to build roots, stems, more leaves and flowers, and then are systematically dismantled and their components are resorbed and redistributed to other parts of the plant.  The remaining framework is then dropped to the soil, most likely to be reabsorbed by the roots after passing through the soil food web.

In this context, looking for the leaves to be green and healthy on a plant in October seems a bit absurd.  Plants that bloom in spring usually shut down in the summer heat, and the ones that bloom in fall are sending all their resources to make flowers and then seeds before a frost comes along.  Another quote from the aforementioned paper again sums it up well:

“The blooming of spring flowers occurs through the utilization of nutrients that have been relocated from senescing autumn leaves. Thus, senescence and death in leaves are active developmental strategies that crucially contribute to the fitness and survival of a plant.”  –ibid

Just look at this beautiful Georgia Aster bloom:

Now take a look at the leaves closer to the base of the stem:

Not nearly as aesthetically appealing as the flower, but part of a totally necessary and natural process on a healthy plant.

Fall is the best time to plant perennials, so now is the time to shop at one of the many plant sales going on in the next few weeks.  If you see some less than perfect leaves, don’t worry. They won’t be there much longer. They too shall pass, and in doing so enable the roots to survive the winter.


Milkweed for Monarchs….and everyone else!

The recent push to plant Milkweed for Monarchs is a welcome development in the gardening community.  Monarchs are dependent on Milkweed (Asclepias spp.) for their survival, as it is the only food their caterpillars can eat.  But it’s not just for Monarchs! LOTS of pollinators visit the flowers to drink the nectar.  I took my camera out to several of our patches of Orange Milkweed (Asclepias tuberosa) yesterday to document a smapling of the variety of insects I see on the flowers.

One of the common names of Asclepias tuberosa is ‘Butterflyweed’ so one would expect to see butterflies.  This female Tiger Swallowtail (Papilio glaucus) is dipping her long proboscis into the nectar rich base of the flower in order to drink it up.  It’s like a built in straw.

A close cousin, the Zebra Swallowtail (Eurytides marcellus) also feeds on the nectar. Much like the Monarch Zebra Swallowtail caterpillars can only feed on the leaves of the plants in a single genus, Asimina, or Paw Paws.

This Common Buckeye (Junonia coenia) was looking a little tattered, as it was probably approaching the end of it’s ~2 week long adult life.  It was still sipping nectar as it rested on the flowers.

Bees also love the nectar from this plant.  Here a Green Sweat Bee (Agapostemon spp.) perches it’s tiny body atop the flower as it sips nectar from inside. It’s just one of the hundreds of species of native bees here in Georgia.

Another Native bee, possibly a Leafcutter bee (I’m not an entomologist), feeding on nectar.

Another possible leafcutter bee: the whitish mat of hairs on the underside of it’s abdomen are used for collecting pollen.  Look closely to the right of the bee and you’ll see an ant sipping nectar as well.

Speaking of Ants, this Fire Ant also found it’s way up the 3 foot tall stalks for a sugary meal. Ants can be pollinators too, and they are responsible for dispersing the seeds of many spring blooming wildflowers such as Trillium and Bloodroot.

This Great Golden Digger Wasp (Sphex ichneumoneus) feeds on nectar as an adult, but like most wasps it hatched from an egg laid on another insect and fully consumed it before the metamorphosis into it’s current winged form.  Golden Digger Wasps are predators to Grasshoppers, Katydids and Crickets.

This Yellow Jacket adult enjoys sugary nectar, but its larvae need a more protein rich diet, which the adults supply by hunting other insects (many of which are agricultural pests).  Wasps are much maligned by humans, but without their predatory behavior we would be literally drowning in bugs and our crops would be decimated.

And finally, not everyone is there for the nectar! This is one of several clever lizards I’ve seen recently near blooming flowers lying in wait for some distracted pollinator to drift too close…..

Milkweed is for Monarchs, but after they have migrated north it’s for butterflies, moths, bees, wasps, ants, beetles, aphids, and even lizards.


Podcasts for the Plant Enthusiast

Podcasts have become a bit of an obsession for me in the past 12 months.  I spend long hours alone in the greenhouse sowing seed trays, dividing crowns, and potting up plants.  I used to listen to music with an occasional audiobook to keep my sanity, but even 10,000 songs on shuffle got old eventually.  In the course of looking for something to entertain and, hopefully, enrich my mind I have stumbled upon a number of podcasts that are now a part of my daily routine.  If you are already familiar with podcasts and how to get them, feel free to skip to the bullet points for my favorites.  If you haven’t ventured into the world of podcasts just yet a short introduction follows.

First: what is a podcast?  It’s a pre-recorded audio production (‘radio show’) that you download or stream and listen to on your phone/computer/internet-connected device.  Most of the shows NPR produces are also available as podcasts, so that should give you a basic idea of the format.  Unlike NPR or radio, pretty much anyone can make a podcast, which means there is a lot a variability and people trying new things.  The upside is that increased access lends itself to a wide variety of shows about specialized and often esoteric subject matter (like native plants).  The only downside I’ve encountered is that sometimes the quality can be lacking for the more specialized subjects (like native plants), but better shows are coming out all the time. Fortunately, most podcasts are completely free to the listener, and there are ratings and reviews that can guide you to good quality productions.

Now, where to get these podcasts?  If you are into Apple products and/or use iTunes, that will be your best bet.  They did invent the podcast, so I’ll give them credit for that and say that most podcasts are available there first.  If you don’t use iTunes, then there are a few other ways to listen.  There are a number of apps, often referred to as ‘podcatchers’ available for free in whatever app store you use.  Download the app, open it up and start browsing for episodes.  I am using Podcast Republic at the moment and I would say it works quite well for me.  The advantage of installing the app is that you can download the episodes for offline listening.  This is especially great for listening in the car or in areas that have poor cell/wi-fi coverage (like the greenhouse) where streaming is not an option.  If you aren’t into the apps and downloads then you can always just listen through your regular web browser on whatever device you use to internet.

Now that the podcast basics are covered, here are the shows that I enjoy and recommend:

  • The Native Plant Podcast – This is a recent find, but has quickly become one of my favorites. I think I might have met the hosts, Mike and John, at the Cullowhee Native Plant Conference back in 2013.  They are both entertaining, knowledgeable guys that run businesses growing and installing native plants in Tennessee and Virginia respectively.  They bring on a guest each week to interview and discuss various aspects of plants, ecology, horticulture, and the nursery industry.  They also end each show by telling short stories about their dogs and having a toast with their guest, usually involving dark beers.  Native plants, dogs and beers: I’m sold.   This episode with Dr. Doug Tallamy is a great introduction to him and his work, and also has some good new info for those already familiar with him.  A quote from this episode with Dale Hendricks that  made me feel better about some of my nursery failures was:“You find a professional grower and you find a person that, for better or for worse, has killed a lot of plants.” It also has a lot of more positive talk about biochar, his role in founding North Creek Nurseries, his new found interest in permaculture, and Paw paws.

 

  • Plants: From Roots to Riches was a BBC radio program, and is now available as a podcast. It’s a good overview of the history of botanical studies, the people that made went exploring all over the globe and the plants they found, collected, studied and grew.  The host, Prof. Kathy Willis is the director of science at Kew Gardens, one of the oldest botanical gardens in the world and a key institution in the development of botany as a proper science.  She enlists her numerous colleagues at Kew and abroad to explain how empire, industry, and agriculture fueled the need for botanical expertise. The episodes are pretty short (about 14 min. each), so the series of 25 went pretty quickly for me.  It’s a very well produced, accessible, narrative of the past 300 years and the revolutions in scientific studies that have changed the ways we view and interact with plants.

 

 

  • In Our Time – Now, we’re getting away from strictly plant based podcasts, but this one has something for everyone.  It’s from the BBC, and the host Melvyn Bragg moderates a panel of experts on a given topic each week and they discuss the history of said topic.  It is often a work of art, a scientific theory or invention, or a social phenomenon.  This episode about Photosynthesis really helped me to visualize the inner workings of plant cells as they make their make their food and breathe.  This episode about the structure of the cell is also fascinating, as are any of the many episodes about astronomy, geology, physics and paleontology. Tons of episodes all chock full of people that have devoted their lives to studying a subject explaining it to a genial British man in fairly simple terms.  You’re bound to learn something new.

Those are all for the plant enthusiast, but others that I regularly enjoy and recommend are: This American Life,  Nerdist, WTF with Marc Maron, Talking Simpsons, You Must Remember This, Radiolab, Invisibilia, Longform, and Snap Judgement.

Happy listening, and if you know of any other good (native) plant-related podcasts recommend it in the comments!


Sweetshrub: 100 Million Years of Blooms

The flowers of Sweetshrub (Calycanthus floridus) are in full bloom right now.   They are a deep maroon color that contrasts nicely with the bright, glossy green of the foliage.  Some plants have more fragrant blooms than others, but if you can find an aromatic one do yourself a favor and take in the smell.  Kind of like strawberries mixed with bananas and a little cinnamon or clove tossed in: there are not many fragrances like it.  The overripe fruits of Sweetshrub’s cousin, Paw paw (Asimina triloba) are the closest scent that comes to mind.  Sweetshrub flowers are unique in appearance as well with their spidery tepals wrapped around a central cluster of anthers. They look like they haven’t quite opened yet.   The color, structure and smell of these flowers differ from most of the flowers that are familiar to us today because they are the results of adaptive strategies first developed over 100 million years ago.

Fossils from Brazil that date to the Cretaceous period (115 million years ago) have shown us the form of an ancestor of Sweetshrub named Araripia.  The fossil “comprises flowers, buds, and leaves, and exhibits features that suggest that “among the Calycanthaceae, especially flowers of Calycanthus are most similar to the flower of Araripia”  The Earth was a much different place 115 MYA to say the least: Only two massive continents, Gondwana and Laurasia, existed and the climate was much warmer and humid.  Dinosaurs roamed the land and insects of all sizes occupied every niche in the dense tropical forests that covered the entire planet.  Plants and insects were just beginning to respond to one another’s adaptive strategies.  These responses were the first steps on a co-evolutionary path that would lead to very complex and specialized forms and life patterns on both sides of the aisle.  Sweetshrub is a living relic from a time before bees when plants were just “learning” that insects could be used to facilitate cross pollination if they are given a little incentive.

This cutaway picture of a Calycanthus bloom shows the minimal differentiation of flower parts as one passes from outer to inner bloom.  Instead of two separate parts, sepals and petals, there are tepals (a half-way-between-the-two structure more commonly found in monocots) surrounding and enclosing the anthers and ovary.  The pollen producing anthers are very similar in their shape and arrangement to the tepals and very simple in form.  The size is really the only variant in the form of the floral parts; There isn’t a lot of specialization.  There are no nectar bearing parts to appeal to bees and butterflies because this flower form evolved before they did.  Beetles were the most likely insects to transfer pollen between flowers as they ate it, so they are meant to appeal to beetles.

Attracting a beetle to a flower is not the same as attracting a bee or butterfly.  First, there are the visual cues.  Beetles, like moths, are attracted to bright white flowers, such as a Magnolia flower (also ancient and beetle pollinated), that reflects light well, especially at night.  Some beetles are also attracted to deep reddish-brown colors, as several other plants known to be pollinated by flies and carrion feeding beetles such as Pawpaw (Asimina spp.), Carrion Flowers (Stapelia spp.) and Pipevine (Aristilochia spp.) have adopted a similar color scheme;  Possibly to mimic wounded or rotting flesh.  Second, there are olfactory cues.  Many beetles evolved to feed upon the carcasses of other animals or their excrement.  An appealing odor to a beetle is not necessarily the sweet smells that we humans most often associate with flowers or fruits.  A spicy, earthy aroma that suggests some sort of decay is more likely to attract a bunch of beetles. Third, there is the form of the flower itself.  Very simple, no complicated pollen sacs or parts that mimic female insects like orchids; no separate disk and ray flowers like asters, just the tepals in a semi-enclosed arrangement around the pollen bearing anthers and ovary.  Beetles aren’t there for the sweet carbohydrate nectar, they just want the protein rich pollen.  In the process of eating, they get covered in pollen grains that will be transferred to the next flower they feast upon.  Mass appeal with vaguely appetizing aromas and easily accessible flowers were the beginnings of plant-pollinator relationships that grew more specific and specialized over the ensuing 115 million years to give us the biodiversity we see today.

Sweetshrub has been a popular cultivated shrub in the south since Europeans arrived, and continues to do well in the nursery trade to this day.  I don’t think that many people, even among those that plant it and enjoy it, are aware of its ancient lineage.

 

Post Script/Cultivation Note:

The seeds of Sweetshrub are large, easy to collect and fun to grow. They also demonstrate a unique and probably ancient strategy of having no energy reserves stored in the seed.  It’s just the seed leaves (cotelydons) wound tightly in a spiral inside the seed coat waiting to unfurl and capture solar energy.

The relatively huge leaves quickly make up for the lack of stored reserves and the true leaves and stem shoot up through the middle of them.


Caterpillar Host Plants: Harvesting Solar Energy for Wildlife

Plants feed wildlife. Plants feed nearly all life as we know it.  They are the base of the food web and produced much of the oxygen in the atmosphere:  Calories to consume and the fuel to burn them.  Even those creatures that consume other animals are dependent upon plants for their survival.  The solar energy that plants convert to sugars and the minerals that they mine from the soil slowly make their way up the “food chain” to even the most carnivorous apex predators via the bodies of their herbivorous prey.   The somewhat outdated concept of the “food chain” can still help to visualize the process of nutrients and energy cycling through natural communities.  These days it is most often referred to as a “food web” and the following graphic is a simplified representation of how it functions with some familiar examples.

food_web

(There should be more arrows going all over the place, a ‘web’ if you will, but like I said, this is simplified to highlight the cyclical nature of the whole process.)

The main points of this graphic I want to focus on are 1) Energy comes from the sun.  2) That energy is harnessed and stored as carbohydrates by plants.  3) The rest of the system depends upon harvesting that stored energy.  Everything else is standing on that foundation of plants

As omnivores, humans have the ability to derive our energy from many sources, and in fact need a varied diet to acquire all of the nutrients necessary for our bodies to function.  It allows us to occupy nearly any area on the planet, but other creatures are not so easily adaptable to new foods and environments.  Survival strategies are often dependent on the seasonal abundance of plant resources with periods of migration or hibernation to cope with food scarcity.  Many insects have evolved to become specialists at feeding on certain types of plants in response to the annual growth cycles in temperate climates.  Typically, an egg is laid on or in a preferred food source, a larva emerges and feeds on that food source until it consumes enough energy to pupate into a winged adult.  The adult then flies off to find a mate, locate another larval food source, lay egg(s), and repeat, if possible, until they die.  Aphids, Wasps, Bees, Moths, Butterflies, Flies, and Beetles all follow this same basic life cycle.

IMG_6108

Black Swallowtail laying eggs on Meadow Parsnip (Thaspium trifolatum)

Butterflies and Moths, collectively known as Lepidoptera, have adapted specialized strategies to feed on plants and mitigate the effects of their defenses in an evolutionary tango over the past 60-100 million years. Through the process of evolution and adaptation the insect’s fate has been inextricably tied to the fate of the plants they consume.  Lepidopteran larvae, commonly referred to as: caterpillars, grubs, tentworms, silkworms, inchworms, armyworms, etc. are a crucial first step in transferring the sun’s energy throughout the ecosystem.  A feature of their specialized feeding behavior is that they have become much more efficient at converting the plant material into proteins with which they build their bodies.  Those proteins are the main food source for many of the creatures that occupy the next trophic level up the pyramid.

Enigmogramma basigera (Pink-washed Looper Moth)

Freshly emerged Pink-Washed Looper Moth (Enigmogramma basigera) and it’s cocoon on a Cardinal Flower (Lobelia cardinalis). Many of it’s larval siblings were dinner for baby birds.

One of my favorite sources for information on butterflies, moths and caterpillars is BAMONA (Butterflies and Moths of North America), a website/database operated by the Butterfly and Moth Information Network.  It has tons of information and resources for anyone looking to learn more or contribute their knowledge and sightings of Lepidopterans.  I spent a little while browsing their database of species and compiled the following list of common names for Butterflies and Moths. See if you can spot the pattern:

“Elder Shoot Borer Moth, Maple Leaftier, Small Aspen Leaftier Moth, Black-headed Birch Leaffolder Moth, Oak Leaftier Moth, Poplar Carpenterworm Moth, Birch Tubemaker Moth, Pecan Leaf Casebearer Moth, Alder Tubemaker Moth, Birch Dagger Moth, Cottonwood Dagger Moth, Tupelo Leaffolder, Fringe-Tree Sallow, Knapweed Root-borer Moth, Poison Hemlock Moth, Virginia Creeper Borer Moth, Fall Clematis Clearwing Borer, Seagrape Spanworm Moth, Walnut sphinx, Poplar Catkin Moth, Yellow Birch Leaffolder Moth, Consular oakworm moth, Oslar’s oakworm moth, Peigler’s oakworm moth, Orange-tipped oakworm moth, Spiny oakworm moth, Pink-striped oakworm moth, Orange-striped oakworm moth, Chestnut Crescent, Live Oak Antiblemma, Oblong Sedge Borer Moth, Large Boxelder Leafroller Moth, Spring Spruce Needle Moth, Fall Spruce Needle Moth, Cherry Shoot Borer, Hickory Leafroller Moth, Hackberry Emperor, Ten-spotted Honeysuckle Moth, Wavy Chestnut Moth”

(These are just a sampling of the species whose Latin names begin with the letter ‘A’!)

The pattern to which I was referring is that the plant that the larva feeds upon is right there in the adult’s name.  Many even tell you the plant part they consume: Leafroller, Shoot Borer, Root Borer, Poplar Catkin, Spruce Needle, etc.   Being a specialist at consuming such specific plants and plant parts confers the advantage of less competition for food resources, but it is a double edged sword.  If that particular plant or part of the plant is not available then the caterpillars cannot survive.   This is where you, the human, enter the picture.  Many of the native plants that were interwoven into the landscape and served their purpose as a larval food source for millennia have been marginalized or removed altogether.  First, agriculture, next urbanization and development, and then landscapers all took turns removing the native smorgasbord and replacing it with foreign, undigestible plants.  Whereas a human might view a Chinese Cherry tree ringed with a border of Monkeygrass surrounded by a freshly mown lawn as a tidy, beautiful landscape, a butterfly looking for a place to feed and nurture her young might see a desert or a wasteland devoid of food.  That same human would probably derive a very similar aesthetic pleasure from an American Cherry Tree ringed with sedges and surrounded by native bunchgrasses, and over 500 species of Lepidoptera would see food and a nursery for the next generation.

Spring is nearly upon us.  That time of year when everyone briefly turns their attention to beautifying their yards before it gets too hot.  Beware the big box stores and their clone armies of gold medal winning plants injected with systemic insecticides.  “Pest Free” is another way of saying “Useless to Wildlife.”  Resist the impulse buy in the garden center.  Do your research and find some plants that will satisfy your aesthetic wants AND wildlife nutritional needs.

blackswallowtails

Black Swallowtail caterpillars on Meadow Parsnip (Thaspium trifoliatum). The plants responded with lush new growth a week later.

 

Postscript:

In the course of researching moths for this article I stumbled upon an account of a moth with a truly unique larval food source: The Gopher Tortoise Moth (Ceratophaga vicinella).  Based on the naming conventions described above what would you guess that Gopher Tortoise Moth caterpillars eat?  If you guessed Gopher Tortoise Shells you would be correct!  More specifically they consume the solid keratin that binds the many plates of a gopher tortoise shell together.  Keratin is the same protein found in your hair and fingernails and other natural fibers such as wool.  The ability to digest and derive sustenance from keratin is shared by a close cousin of the Gopher Tortoise Moth: the common Clothes Moth that loves to eat (you guessed it!) wool clothing and rugs.  The amazing part of this relationship to me is that there used to be such a surplus of Gopher Tortoise shells laying around that their abundance encouraged an entire new species to branch off and specialize in consuming only tortoise shell keratin.  Sadly, this strategy has proven to be risky with the decline of Gopher Tortoises, which is a direct result of the decline of the Longleaf Pine-Wiregrass ecosystem (and its seasonal fires) on which they are dependent.   There are hundreds of other animals and insects that depend on Gopher Tortoises and their burrows in some form to survive, and none of them are doing well.  Bring back the Longleaf!