Pin the Plant on the Triangle

This semester, one of the classes I’m teaching is herbaceous plants, and I’m taking the class beyond the usual discussions of annuals and perennials.  From studying herbaceous plant communities, one of the most useful concepts that I’ve learned in recent years is the classification of a plant’s survival strategies.  

I’ve written about it before here and here.  As a refresher, Grime pitched that plants had three strategies based on environmental factors.  

  • COMPETITORS are plants that take advantages of any and all resources they can muster.  They grow tall and wide to take out the competition.  Usually these stalwarts are perennial in nature, and they grow where stress and disturbance are nil.

  • STRESS-TOLERATORS are plants that have adaptations to ensure survival when stress arises and conditions deteriorate.  They are usually perennial and can take many years to flower from seed.

  • RUDERALS are short-lived annuals or biennials that are frequently exposed to some type of disturbance, which has selected for plants that quickly produce seed.

Usually, this strategy is visualized using a triangle (much like the soil texture triangle!) where a certain species can be shown to be—pulling some numbers out of the air—say, 70% competitor, 20% ruderal, and 10% stress tolerator based on the characteristics they exhibit.  

A figure of Grime’s triangle from Pierre et al. (2017) titled A global method for calculating plant CSR ecological strategies applied across biomes world-wide. As you can see the authors attempted to classify plants across the globe based on their t…

A figure of Grime’s triangle from Pierre et al. (2017) titled A global method for calculating plant CSR ecological strategies applied across biomes world-wide. As you can see the authors attempted to classify plants across the globe based on their tendency to be a competitor, stress-tolerator, or ruderal.

How do you take this concept from theory to application for students? Much research and data collection is needed to be able to precisely place a plant on the triangle.  Can it be done in a more simple fashion?  

After we covered the CSR theory in class, I did an activity with students.  I gave small groups (three to four) a list of seven different herbaceous plants and asked them to look up information and pictures online and try to determine where on Grime’s triangle it would fit.  I drew a triangle on the board labeling the sides and gave them markers and half sheets of paper for writing plant names.  

I then challenged them in pin-the-tail-on-the-donkey fashion (no blindfolds or sharp objects though!) to figure out where on the triangle the species would go by searching for it online.  Students looked for tendencies to spread, cover large areas, form large clumps, and/or have rhizomes (COMPETITOR); tendencies to produce copious amounts of seed, occur in areas of disturbance, and/or be short lived (RUDERAL); and tendencies to live in a stressful habitat, take a long time to flower, and/or have storage organs (STRESS-TOLERATOR).

One by one they started coming up and making educated guesses.  I stood by the triangle to offer advice and suggestions.  Some hit the nail on the head while others needed a little bit of coaxing to the right place.  

At the end, we went over the 20 or so species I provided as a challenge.  Again, I explained that while some species neatly fit into one group, some straddle the fence like Liatris elegans.  It has a corm (a stem-derived storage organ indicating some level of stress toleration) yet produces copious amounts of seed (traits of a ruderal).  

Pin the plant on the triangle—a fun game to teach students about plant survival strategies. Based on your plant knowledge, how do you think they did?

Pin the plant on the triangle—a fun game to teach students about plant survival strategies. Based on your plant knowledge, how do you think they did?

As gardeners it’s very helpful to think about flora in this way.  It helps us anticipate how plants will perform.  It explains why Gaillardia and Aquilegia don’t live long as perennials (ruderals), why Mentha and Monarda spread like crazy (competitors), and why Trillium and Narcissus  take 3–7 years to flower from seed (stress-tolerators).   It also allows us to envision how to combine plants.  Maybe put that runaway competitor in a drier spot to keep it from taking over creation?  Or, sow some ruderals in between the stress-tolerators to keep weeds down.  

If students can decide approximately which section of the triangle plants fit in during a 15 minute activity using search engines, then we can by watching how plants grow over the course of a year. 

So, that’s your homework for the season. Draw a triangle and see if you can’t plot where the species in your garden fit.

Chillin' for a Peach Fillin'

My first peach tree is flowering.  ‘Flordaking’—and, yes, there is not an i missing. The name gave me pause the first time, too—arrived last fall in a six-foot-long box. Upon opening said package, to my surprise a six-foot-tall Prunus persica was inside.  I guess that’s what happens when you buy a five-gallon tree.  

 
Present, past, and future flowers of ‘Flordaking’ peach

Present, past, and future flowers of ‘Flordaking’ peach

 

I sited it in our edible patch.  I had initially set aside this approximately 100 × 100 ft fenced area to be an orchard, but after mental iterations, it became clear after some damage from deer, boar, rabbits, and armadillos that the area would be better suited for more annual production since they were obliterated elsewhere.  I slated the back third edge-habitat area for fruit trees, and the rest of the front was for cut flowers and veggies.  

While I’m more of a nectarine person myself, Karen likes them; therefore, in the orchard a peach went.  The reason I chose ‘Flordaking’ is because of its low chill requirement.  In horticulture we talk about chilling hours as a measure for how much cold a plant must receive before it flowers, and while there are different approaches to calculate that number, let’s say that we count the hours under 45F.  

I teach students that a tree’s chill requirement is an alarm clock. It is a wonderful adaptation that some temperate trees have to the extreme stress of being exposed to cold temperatures in the winter.  Just like some people need 6 hours of rest and others need 8 (…or 10), some peaches need a few hundred hours down south while others further north require 1000 hours.  

Chilling causes sugar levels in the trees to increase and hormone levels to change.  The tree must be exposed to a certain amount of chilling to be able to flower.  If not enough chilling is perceived, then the plant can’t flower because enough metabolic changes haven’t occurred yet.  The alarm clock hasn’t gone off and the tree can’t wake up.  In fact, planting a high chill requirement tree in the south where we have warm winters every so often may result in the plant being extremely delayed in growth.  

‘Flordaking’ is estimated to need about 400 hours of cold.  Released by the University of Florida in 1978, it’s touted to be one of the best varieties for us to plant in zone 8.  

 
A honeybee dusted with pollen. For fun, notice how the stamens (filament structures) change from orange in a new flower opening to yellow where they are shedding pollen.

A honeybee dusted with pollen. For fun, notice how the stamens (filament structures) change from orange in a new flower opening to yellow where they are shedding pollen.

 

The appearance of petals in recent weeks indicated that the snooze wasn’t pushed. Instead, the tree is rising and shining. It is pure delight to watch the petals unfurl.  The other afternoon I stood and watched a bee work the sparse flowers on the little tree in the waning light.  It wasn’t very skittish and allowed me to get close and observe it swimming in the stamens to get the nectar at the center. While peaches are self-fertile and one tree will produce fruit, I’m going to add another one or two to the patch for some diversity.  

This list has been helpful picking some low chill varieties for our garden.  Maybe it’ll help you, too.  

The Avoidance Zone

Don’t you love learning?  Wrestling with a concept, and finally putting the puzzle pieces together to see the bigger picture.  That’s been me lately with this amorphous concept called the avoidance zone.  

Well, longer than lately.  It's been something I've wondered about since childhood, but I didn't know it was called that. 

Growing up in west Tennessee I loved to go romping o'er hill and dale searching for wildflowers.  But, finding any was rare.  I can count on my hands and toes the number of really unique native wildflowers I found within a mile of my house (Erythronium albidum, Trillium recurvatum, and Phlox divaricata near the old creek; Arisaema triphyllum in the woods by the river; and on roadsides and in fencerows Tipularia discolor, Yucca flaccida, Vernonia gigantea, Podophyllum peltatum, Sedum pulchellum, Pycnanthemum tenuifolium, and Rudbeckia sp. along with a few other yellow Composite species I never keyed out.  That’s pretty much it. 

I felt so gypped. These books I read showed forest floors and prairies covered with a plethora of plants and blooms as far as the eye could see. Even traveling east towards Nashville you could see Trillium and Geranium going 70 mph on I-40.  I lived in the country.  Rural America.  There should be ample flora for a budding young botanist.  

Why weren’t there more wildflowers in west Tennessee?  It wasn't that we couldn't grow plants.  What flora was there grew very well.  We had fertile soil, and we received abundant rainfall.  I felt I should be finding more.  Go east or west, and the number of different kinds increased.  I assumed the reason why was because the region had been farmed to death.  Fields and pastures now occupied my would-be floral dreamland.  

But, had the species diversity been richer before conventional agriculture arrived on the scene?  I wasn’t certain.  Richer, of course, in a technical sense.  Species richness is an evaluation of how many DIFFERENT types of species are present in an area.

Once in a conversation with one of my undergrad professors Dr. Nancy Baushaus, it arose that the same phenomenon is observed with mammals. The further you go east toward middle Tennessee or the Ozarks westward, the richness of mammals increases.  This observation followed the same trend as what I saw with flora and made sense if we assume that the upper levels of the food pyramid are limited in their richness by the layers of species beneath them.  The pyramids in Egypt don’t get wider as you climb.  

* * *

A few years after I left home for grad school I became aware of the Biota of North America Program (BONAP), a great website for finding county-level distributions of plants species. With that data they help visualize what species occur where, and they can run analysis to see the richness of species diversity in different regions. Browsing the website I discovered this map...

All credit to Biota of North America Program for generating this informative map.  While a legend doesn't exist for the map, green has the highest number of plant species followed by lighter greens and yellow, followed by tans and browns for lo…

All credit to Biota of North America Program for generating this informative map.  While a legend doesn't exist for the map, green has the highest number of plant species followed by lighter greens and yellow, followed by tans and browns for lowest diversity of native vascular plants.  There is more information on the website about the terminology in the map.  

...and that I had been living my childhood in a region called the… dun dun DUN... AVOIDANCE ZONE.  It's like a little yellow desert island in a green sea of vegetation in the south.  Maybe the dearth of wildflowers wasn't my imagination.  Maybe there was something else going on here.  

But, what?  And, what is this thing called an avoidance zone?  The BONAP website states it is where "flora [is] limited by [a] lack of suitable habitat for a diverse flora, whereby widespread species may have a range gap in this area rather than having its own flora.  

The inner first grader in me came out yet again as I asked another why.  Why a gap?!?  There's plenty of resources in west Tennessee, especially with decent soils and ample rainfall.  Years passed as this question sat on the back-burner in my mind, occasionally being stirred from a conversation here and there with a colleague.   

Enter Thomas Rainer.  He turned my mental stove up to high when he presented at Speaking of Gardening in Asheville this past August.  Rainer said during his talk that stresses in a landscape actually increase plant diversity.  

Wait, what?!  Why would stress increase diversity?  It seemed to go contrary to everything that I knew about organisms in their environment.   If environments are too stressful, then hardly anything can grow well.  (*Cough* Antarctica *Cough*)

Several Google searches later with keywords including species and stress and diversity yielded nothing.  But, here is where things got interesting in my thinking.  I flipped the increasing-stress-then-increasing-diversity hypothesis on its head and asked, "If stress increases diversity, could an absence of stress or low stress decrease diversity?"  I.e. better conditions resulting in less types of plants growing in a region.  Perhaps, but again I wanted to find hard evidence why.

* * *

A few weeks ago, I started reading Sowing Beauty by James Hitchmough.  (Side note:  I’m only a few pages into the book.  It’s a great, great read if you want to learn more about how ecology can influence gardening.)

I found the answer!!! 

James wrote that resource-rich environments have low species diversity because the competitor plants present outcompete other species (see my prior post to learn more about the three survival strategies of plants). That’s what they’ve evolved to do, to use resources more efficiently.  And, with their resource-harnessing prowess, they tower over others and crowd them out.   

Mind. Blown.  I think competitor species created the avoidance zone.  West Tennessee habitat is suitable, perhaps too suitable.  I was amazed that it could be not directly due to resource availability or habitat suitability but an indirect effect from some species being resource hogs.  

On a whim, I started looking at factors for plant growth across the country like soil fertility.  The map below was created by Bradley Miller, Randall Schaetzl, and Frank Krist, Jr. (researchers at Michigan State University and United States Forest Service) to illustrate how productive soils are.  Orange soils are less fertile, pink is in between, and purple/blue soils have the highest fertility.

All credit to Bradley Miller, Randall Schaetzl, and Frank Krist, Jr. for their incredible work creating this soil fertility index map.  The link in the caption provides a more detailed legend, but again yellow/orange soils are least fertil…

All credit to Bradley Miller, Randall Schaetzl, and Frank Krist, Jr. for their incredible work creating this soil fertility index map.  The link in the caption provides a more detailed legend, but again yellow/orange soils are least fertile, pink is in between, and purple/blue soils have the highest fertility.

To compare with the original BONAP map, I overlaid the two and created the nifty gif below. 

Avoidance-Zone-gif2.gif

Psychedelic, huh?  While I haven’t done any statistical analysis, it appears that patterns exist between the two maps.  As soil fertility increases (map gradients go from yellow/orange to pink to purple/blue), the species diversity decreases (map gradients go from green to yellow to brown).  A few that popped out to me are listed below.  

  • Orange on the soil fertility map corresponds with green/dark green in the Ozark Endemism Zone, Southern Appalachian Endemism Zone, Apalachicola Endemism Zone, and Coastal Appalachian Tension Zone.

  • Lower Mississippi Alluvial Avoidance Zone (aka home) is pinker in soil fertility than surrounding orange regions and has yellow/tan species diversity compared with the surrounding green/yellow green areas.

  • Great Plains Low Diversity Zone has a blue/purple color for soil fertility and tans and browns for species diversity (notice the orange spot in Nebraska where species diversity actually goes up a little)

Of course, soil fertility won't explain the entire interaction as there are other factors that influence plant growth, and not every part of the map follows the colors exactly.  But, I can see patterns, and this observation helped me answer why we had low species diversity in west Tennessee.   

* * *

The concept that at some point decreasing resource availability and increasing stress species has to result in a drop in diversity still bothered me.  It is just logical, so how do we fit this thinking into a plant community model?

I was looking up some information recently on John Philip Grime who conceptualized the competitor, ruderal, and stress-tolerant model, and I came across his hump-back model of species diversity that really neatly wraps up much of what I've been mulling over since my childhood. 

 
Figures from Michalet, R. and B. Touzard.  2010.  Biotic interactions, biodiversity, and community productivity, p. 59–78. In: Francisco Pugnaire (ed.). Positive Plant Interactions and Community Dynamics.  CRC Pres…

Figures from Michalet, R. and B. Touzard.  2010.  Biotic interactions, biodiversity, and community productivity, p. 59–78. In: Francisco Pugnaire (ed.). Positive Plant Interactions and Community Dynamics.  CRC Press, Boca Raton, FL.

 

Grime used data he collected from British plant communities to generate the above models.  Curve B is of interest to this post.   Again, species richness is an evaluation of how many DIFFERENT types of species are present in an area.  As environmental stress increases, competitors can't grow as well; therefore, other species that can handle stress can survive.  However, eventually the stress becomes so great that even the stress-tolerant species begin to decrease in number. 

If you'd like to know about Curve A, it represents increasing management/disturbance.  The more frequently plants are killed due to fire, flooding, etc. decreases the competitors so that other plants can grow; this stress increases diversity until the disturbance becomes so great that even the ruderal species decrease in number. 

* * *

So, what’s the application of this?  If I’m a common gardener, what do I care?  

One is a repeat of what many have been writing—stress can be and is an asset in our gardens.  We have a "more" mentality for the resources our plants need like water and fertilizer, but perhaps stressing things a bit would help us be successful with more species. 

I also think understanding this hump-back model can make us better gardeners and designers in combining different species together.  If we have a sense of what survival strategy a species uses, we can make sure that we aren't creating mini-avoidance zones in our gardens.  

Finally, I don't think that the area I grew up in should be called the avoidance zone.  I mean if you were a plant would you want to grow in an area called that?  Kidding aside, yes, the region is a gap between higher species diversity areas, but I don’t think it accurately explains why.  Plants were not avoiding west Tennessee.  They were just being outcompeted.  

Mulch Happens

The other night a phrase in The Holistic Orchard by Michael Phillips stopped me reading mid-paragraph.

"Mulch happens."

I was surprised because I feel like horticulture is moving away from wood mulch with the interest in mixed plantings and covering the ground with plants.  Or, at least with that desire in mind (like here and here) if we all aren't quite on board yet. 

The action of mulching just isn't sustainable.  Depending on dead organic matter to prevent weed growth around perennials in place of living plants is a fallacy that will have to constantly be remedied.  It is Sisyphean task.  Hardwood mulch also doesn't naturally occur, except maybe under a fallen, decaying tree.  As Thomas Rainer says, you won't find mulch circles in the forest. 

So, does mulch really happen as Michael wrote?  To make sure that I'm not taking the quote out of context, here it is in full: "Nature builds soil from the top down: Leaves fall, tree limbs decay, mulch happens.    

In the sense that we are used to seeing hardwood mulch strewn across the landscape, no .  We do have an organic layer present in most soils, but it's not a few inches thick of hardwood.   Instead, it's dominated by a mixture of the abscised and the fallen, the green and the brown, the leaf and the stem.  

Michael wrote that when he mentioned mulch he was not talking about recalcitrant hardwood mulch that takes years to decompose.  Instead, he was discussing ramial wood chips, a type of organic matter that comes from branches and stems that are less lignified and higher in nutrients.   He advocated applying these wood chips in random patches throughout the orchard to feed the soil.  His approach is to chop stuff up and then dump piles of it around his fruit trees. They don't form a solid cover, which encourages grasses and other forbs to grow to create a multiculture.  He stated most fruit trees originated along ecosystem edges.  Introducing rough, slowly decomposing organic matter helps to improve the soil similar to these plants' native habitat.  While I haven't studied the use of these ramial wood chips much but want to learn more, the logic behind their use seems sound.  

What I think is fascinating for these perennial cultures—mixed plantings and the use of ramial wood chips in orchards—both schemas ask the question how can we emulate nature and try to enhance the biological systems already in existence, especially with covering the soil.  In both cases mulch happens, just not the way that we traditionally think about mulch. 

Tendrils from Speaking of Gardening 2017

NorthCarolina-IL.jpg

In August I presented with several other outstanding horticulturists at the Speaking of Gardening Symposium in Asheville, NC.  It was a terrific educational event to attend in the mountains, jam-packed with great ideas and awesome plants.  Below I offer three "tendrils", paraphrased nuggets of knowledge or interesting thoughts that you can really wrap your mind around from each speaker.  

 

THOMAS RAINER | PLANTING IN A POST WILD WORLD

  1. Planting design in the public sector has to be legible at 45 miles an hour.

  2. With native plants there is so much focus on where they are from but not enough on how to cultivate them.  When people plant things and then see them fail, they get depressed. They blame native plants.

  3. Use tools like plants shape and plant sociability to determine how to combine plants together.  For example, everything about Asclepias tuberosa is an adaptation to where it grows and what it grows with. Deep roots grow through grass roots, and the leaves are able to emerge through shady areas in a prairie.  

ROY DIBLIK | BEYOND THE USUAL: PLANTING THE LURIE GARDEN WITH PIET OUDOLF

  1. When planting the Lurie Garden, I wasn’t accurate.  I stepped it off.  It took a day and a half to do the site. It's not a building; you don’t have to be super accurate.

  2. Teachers come in to help maintain the plantings with students.

  3. They selectively prune the Salvia river at the Lurie Garden.  If you cut Salvia 'May Night' back, it may never bloom again that year.  'Wesuwe' is the fastest rebloomer. If you cut it back, it reblooms in three weeks.

DAN LONG | GROW UP! USING VINES AND CLIMBERS

  1. Clematis need something slender to hang onto.  For other climbers don’t put anchors right up against the wall because the wrappers can't get through that narrow space. Also, being that close to the wall results in low air circulation.

  2. Campsis likes to bloom on horizontal stems or those that droop.

  3. Tropical Aristolochia species can kill pipe vine swallowtail larvae.

PATRICK MCMILLAN | BLURRING THE LINES BETWEEN NATURE AND CULTURE AT THE SOUTH CAROLINA BOTANICAL GARDEN

  1. Every decision we make at the South Carolina Botanic Garden we ask is this good for life.

  2. BOTANICA CAROLINIANA features letters from early explorers like Mark Catesby that have first hand accounts of South Carolina that were written to Britain.  These perspectives help us understand what South Carolina looked like back many years ago and in some cases helps us find where plants were and still are today.

  3. We filmed Ruby-throated Hummingbirds and captured the fastest video footage of them ever. These birds lift themselves because they flap their wings in a figure-eight motion, which generates lift on both the forward and reverse flap.  And, as you can see at the 1:50 mark, they can fly backwards and upside down!

THOMAS RAINER | THE GARDEN OF THE FUTURE: REIMAGINING THE AMERICAN YARD

  1. Turn wall-to-wall carpeting of grass into turf rugs.  The lawn can make the planting look better. It can be a frame to the wilder areas.  Use lawns like a clearing in a meadow.  

  2. Landscape plugs are best for designed plant communities. Most plugs are grown as liners and sold to pot up; thus, liners can dry out fast in the ground.  Deep landscape plugs are longer and deeper.  Make sure that the plugs have good roots.  They can be soaked in buckets or trays before planting. 

  3. Many perennials maintain green rosettes or basal foliage during winter so that winter weeds like chickweed can't grow.

LARRY MELLICHAMP | THE WONDERFUL WORLD OF FERNS

  1. Sensitive fern (Onoclea sensibilis) gets it's name because it is sensitive to freeezing and can burn from cold temperatures.

  2. Ferns can be divided when actively growing.  SUPER IMPORTANT (His emphasis).  Do not disturb the roots and cut off leaves at same time.  You can do either/or but not both.  Broken fronds can still function well.

  3. Lycopodium spores are pyrotechnic!  Light them, and they explode!  The spores were used to make fireworks. 

ROY DIBLIK | THE KNOW MAINTENANCE PERENNIAL GARDEN

  1. First year, install the matrix, and then you keep plugging things in to enhance it over time.

  2. You can wait and plant aggressive plants like Solidago after five years to reduce their competitiveness.

  3. I spray the grass with glyphosate, and then I use a two cycle engine and auger to install the plants into the ground.

A Pioneer in the Smokies

The Smoky Mountains are a magical place for me.   Always have been.  Always will be.  Probably once or twice a month I have dreams where I'm driving along the twisted roads or hiking the fabled trails.  It's my parents' fault.  They took my sister and me there when I was nine, rolled down the window, and herded clouds into the car on the high mountain tops.  I was hooked.  

I like to visit the mountains once a year or so, and last spring, Karen and I planned a visit to the Great Smoky Mountains National Park over my long Easter break.  I, of course, started searching for great places to see wildflowers, and reports for Greenbrier suggested it was peak for early spring bloom.

Greenbrier is no stranger to me.  It's one of my favorite places to visit.  When I was in grad school in Raleigh and met my family for a long weekend in Gatlinburg, I'd always pass Greenbrier on Highway 321.  Sometimes if I was a bit early, I would stop and say hi to the craggy creek.  

The Little Pigeon River gurgles through Greenbrier.

The Little Pigeon River gurgles through Greenbrier.

For this visit, we would be staying a bit longer in Greenbriar to hike Porters Creek trail.  I had seen pictures online of the Phacelia fimbriata (fringed phacelia) in full bloom, and the effect looked incredible, like a carpet of white wildflowers in the woodlands.     

We parked for the day along the car-crowded road, which suggested we wouldn't be alone for the hike.  We walked for about an hour passing old stone fences and traversing mighty hemlocks.  We hadn't seen many flowers in bloom till we came to a narrow bridge.   

The narrow bridge along Porter's Creek trail.  Hikers provide a sense of scale.  

The narrow bridge along Porter's Creek trail.  Hikers provide a sense of scale.  

However, once we crossed over, it felt a bit like entering Narnia because suddenly we were surrounded by snow!  

Where's the lamppost?!

Where's the lamppost?!

Ok, green and white snow.  But, it was everywhere!!!  

Phacelia fimbriata o'er hill and dale

Phacelia fimbriata o'er hill and dale

And, it continued for about a quarter of a mile.  It was breathtaking to see so many of one organism en masse.  

 
A moss-covered log rests in a blanket of Phacelia

A moss-covered log rests in a blanket of Phacelia

 

Some of it even grew on rocks.  

Fringed phacelia thrive on a boulder, no doubt supported by a layer of detritus and abundant rainfall during the winter and early spring.  

Fringed phacelia thrive on a boulder, no doubt supported by a layer of detritus and abundant rainfall during the winter and early spring.  

 
A close up of Phacelia fimbriata.  The flowers were about the size of a dime.  

A close up of Phacelia fimbriata.  The flowers were about the size of a dime.  

 
Much like footsteps on fresh fallen snow, a trodden path manifests through the Phacelia.  

Much like footsteps on fresh fallen snow, a trodden path manifests through the Phacelia.  

In horticulture design we discuss how the effect of repetition is calming and creates harmony in the landscape.  In fact, just a few weeks ago I shared with my class that seeing the same plant used multiple times in the landscape creates a sense of comfort.  Much like when you travel to a foreign place and see familiar logos or icons. 

So, why so many of one organism?  No human planted this monoculture.  This is nature. 

From my environmental biology background, I learned to ask the question why does a species grow this way?  There have been efforts to classify plants based on their survival strategies, and Grime's universal adaptive strategy theory groups plants broadly into three different categories.  

  • COMPETITORS are plants that take advantages of any and all resources they can muster.  They grow tall and wide to take out the competition.  Usually these stalwarts are perennial in nature.

  • STRESS-TOLERANTS are plants that have adaptations to ensure survival when stress arises and conditions deteriorate.  They are usually perennial and can take many years to flower from seed.  

  • PIONEERS (aka RUDERALS) are short-lived annuals or biennials that are frequently exposed to some type of disturbance, which has selected for plants that quickly produce seed.  

Like most human-made models, plants don't fit neatly into these classifications.  Most plants are a blend of at least two strategies, much like you see below.  

This figure from Pierce et al. (2013) illustrates how one can classify plants as competitors, stress-tolerant, or pioneers/ruderals.  The placement of the symbol equates to what percentage of each strategy each plant exhibits.  

This figure from Pierce et al. (2013) illustrates how one can classify plants as competitors, stress-tolerant, or pioneers/ruderals.  The placement of the symbol equates to what percentage of each strategy each plant exhibits.  

But, thinking about these survival strategies can help us anticipate how plants will perform over time in our gardens.  They help us understand why stress-tolerant Trillium can take several years to flower from seed, or why pioneer Gaillardia can die in our gardens after a few years.  (If you want to read more about Grime's theory, might I suggest Planting in a Post Wild World by Thomas Rainer and Claudia West and Garden Flora by Noel Kingsbury).

In the case of the Phacelia that surrounded us on Porters Creek trail, we were looking at a pioneer-type species based on its short life span and the sheer abundance of plants.  Phacelia fimbriata is a winter annual.  It germinates in the fall, flowers the following spring, and dies after spreading seed.  It also takes advantage of the full sun that filters through the barren canopies during winter and early spring.  

This environment doesn't match my traditional concept of a pioneer species before I learned of Grime's theory.  I usually associate pioneers with species that come in and colonize an area after all vegetation has been removed, and yet around us were towering trees clambering toward the climax community.  But, as Larry Weaner and Thomas Christopher discussed in Garden Revolution, sometimes disturbance only affects a layer of vegetation and not all plants are removed.  

As I began to ponder what disturbance the Smokies get, my mind immediately went to the horrible wildfires that ravaged Gatlinburg this past fall.  Research in the Smokies has shown that fires on average have happened once every 5 to 7 years between the early 1700's to about 1930.  If this pattern was the same for millennia before, it's easy to see how this species evolved to survive frequent disturbance.  

We also encountered a few other spring ephemerals along our hike, and many were like old friends.  I hadn't them seen in a while, but they still brought a smile to my face.  

 
Dicentra cucullaria (Dutchman's breeches). See the hole? Looks like someone forgot to patch their pantalones before hanging them out. 

Dicentra cucullaria (Dutchman's breeches). See the hole? Looks like someone forgot to patch their pantalones before hanging them out. 

 
Trillium grandiflorum in all its grandeur.  

Trillium grandiflorum in all its grandeur.  

The freckled petals and coffee-colored stamens of Erythronium umbilicatum (dimpled trout lily) are a delight in spring.

The freckled petals and coffee-colored stamens of Erythronium umbilicatum (dimpled trout lily) are a delight in spring.

Anemonella thalictroides (rue anenome) occasionally dotted the forest floor.

Anemonella thalictroides (rue anenome) occasionally dotted the forest floor.

 
I assumed before we went that we would see Sanguinaria canadensis (bloodroot) everywhere, but I only saw one in flower.  It was actually right as we were coming back to the parking lot.  

I assumed before we went that we would see Sanguinaria canadensis (bloodroot) everywhere, but I only saw one in flower.  It was actually right as we were coming back to the parking lot.  

 

Overall, Porters Creek trail was a great hike, and we both enjoyed the beauty of the spring wildflowers.  But, the wildflowers weren't my only goal for the trip.   

 
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I also had plans to propose to Karen the next morning after the Gatlinburg Easter sunrise service.   She said yes, and the Smokies became even more special for the both of us.