Monday, October 24, 2011

Field Notes--Orchids & Sundews of Tallulah Gorge

Tallulah River as seen from the hydroelectric station.

October 14, 2011
It is just dawn and I am riding in the back seat of the Atlanta Botanical Garden’s Subaru heading toward Tallulah State Park. The conversation up front is making me want to climb out the window.  Matt Richards and Ron Determann, ABG’s Conservatory Director, are talking about the ecological losses Ron has witnessed in 30 years of plant conservation. 

“There aren’t really any natural areas left in Georgia.  Not really,” he says. “Just pockets with refugia of rare plants.”

The main problem, as he sees it, is the heavy use of herbicides used to control weeds along roadsides, under powerlines, and even along paths in natural areas visited by the public.  The method formerly used, which is less destructive, is mowing.   But that takes more people and equipment, plus you have to mow more often than spray—at least initially.  The result, according to Ron, has been the destruction of most roadside ecology. 

Sarracenia leucophylla, Conservation Garden @ ABG
Now, you might not think that native plants, and certainly not rare plants, grow in highway medians or under powerlines, but they do. The white-top pitcher plant (Sarracenia leucophylla) was thought to be extinct in Georgia until it was found growing in a powerline right-of-way in 2000.[i]  Similarly, one of the few Georgia populations of Tennessee yellow-eyed grass (Xyris tennesseensis) clings to the greenspace in a highway off ramp.[ii]   

As counter-intuitive as it seems,  nutrient-poor sites also harbor greater biodiversity.  Repeatedly spraying for weeds builds up decaying vegetation, which enriches the soil making it more hospitable for weedy growth.  So instead of a diverse roadside ecology, you get a few species of invasive weeds growing lush and tall.  Naturally, the invigorated weeds require more frequent of spraying.  And so it goes.

The other nasty side-effect of using herbicides is the harm they can do to amphibians.  Herbicides with surfactants are not to be used in wetlands, but they very often are.  The surfactants clog the breathing pores of frogs and other creatures, killing them.

In addition to weed suppression, herbicides are injected into tree stumps to prevent re-sprouting.  The practice is thought to be safe for the creatures that live around these stumps, but Ron doesn’t think so.  He describes finding skeletons of 30 year-old bog turtles that died after stumps around their habitat had been poisoned.

At this point in the conversation, I can take no more. It’s barely light out, and in the morning I am especially vulnerable to despair.  I pull photos of plants on my phone for Ron and Matt to identify. It’s not that I don’t want to hear it; I just need my doses of toxic knowledge at non-lethal levels.


Ron Determann: Conservationist & horticulturalist extraordinaire.
Today we will not be visiting a roadside refugia, but climbing into Tallulah Gorge, one of Georgia’s most beautiful places, to look for the monkeyface orchid (Platanthera integrilabia) and some of its friends.  We hope to collect seed to bring back and grow in the tissue culture lab.  We’ll keep some seed and plants for back up and outplant seedlings to augment the natural population.  Growing things is Ron’s especial gift.  He has brought rare and endangered plants into cultivation that no one else has been able to grow.  The tissue culture lab that Matt runs at ABG is named after Ron.  

The tram making its very slow yet precipitous journey.
The orchids were sighted growing near the floor of the Tallulah gorge, nearly 1,000 feet down, alongside the Tallulah River.  The river is no longer the roaring terror that earned it the name “ the Niagara of the South.”  Dammed in 1913, the Tallulah River’s six falls have been quieted.

Nevertheless, we still have to find a safe place to cross the river to reach the orchids.  Brian Estes of Georgia Power knows just the spot and he's arranged a special treat for us.
Almost there. See the folks at the bottom?
We are taking the a tram that runs strait down the face of the gorge to the hydroelectric station below.  Hiking down would be pleasant, but that would take three hours round trip, leaving less time to hunt orchids.   

Climbing into the tram we are initially cautious of the open doors but are soon hanging out the sides taking photographs of the odd combination of flora growing on the slope:  natives, exotic invasives, and wetland plants taking advantage of the water flowing from tiny leaks in the penstock pipes that take water down into the hydroelectric turbines. 

Forging the Tallulah River
Our ride over, we leave the tram and put in earplugs so that we can walk through the noisy power station and begin our final descent into the gorge.  Soon we are scrambling over rocks and through trees and shrubs looking for a shallow place to cross the river.  Brian finds the spot and one-at-a-time we make our way through the water and over the rocks slick with moss. 
We are on the other side less than three minutes before Matt finds orchids.  We collect seed capsules and move to another spot.  The growth of shrubs is dense and the footing is uncertain, and everyone manages to grab hold of poison sumac at one time or another.  Having inadvertently nuzzled the stuff, I have a vision of my face 3 days from now erupting into painful blisters.  

Poison sumac in its autumn colors.

I next see my companions gathered at a seep where water has collected into what looks like a shallow pool but Brian has warned us is actually waist-deep silt.  Matt and Ron collect more seed.  I see Parnassia asarfolia in bloom, which I saw for the first time last week while collecting Isotria with Matt.  We thought we’d have time to stop and take photos on the way out, but no such luck.   
Parnassia asarfolia
While I am carefully photographing the exquisite blossom, the rest of the group continues the ascent.  The next thing I know I am alone.  I start to climb and call, climb and call.  At last I hear an answering voice.  By the time I catch up, I’ve lost my lens cap and some of my composure.  My hair is full of twigs and leaves. 

Everyone is standing around what may be the same seep only much higher up.  Sphagnum moss grows thickly at the edges of the wet rock face, and on the face itself are tiny round-leaf sundews, Drosera rotundifolia.  The red hairs on their leaves glisten with mucilage, a sweet but also sticky substance that lures insects to their doom.   
Sundews appear to be growing in light film on rock face.
Once stuck, the hairs bend inward and the leaf begins to fold over the insect. Meanwhile glands on the hairs secrete enzymes to dissolve and digest the insect.  Several days later, the meal complete, the leaf will unfold, ready to ensnare its next victim.  Carnivorous plants live in nutrient-poor conditions like this seep, catching and eating insects to supplement their diet.

The Drosera rotundifolia growing so abundantly in this seep is the same species of sundew that Charles Darwin prodded with everything but the kitchen sink.  To see what would make the sundew move, Darwin placed in its hairs—he called them tentacles—meat, dead flies, bits of paper, wood, dried moss, sponge, cinders, chalk, wadded strands of hair, and shards of glass.  What he found was that when repeatedly touched by minute objects, the tentacles would invariably enfold the object.  Meat, egg, and, of course, insects the plants retained and flooded with digestive enzymes until consumed. Innutritious material like glass and cinders the leaf released.

(Drosera rotundifolia)
Leaf (enlarged), tentacles on one side inflected over a bit of meat placed on the disc.
 From Charles Darwin's Insectivorous Plants (1875).  Drawing by his son George.
In Darwin's experiments not every touch resulted in movement.  Drops of water and other heavy pressures did not cause the tentacles to bend. Darwin concluded that thanks to this selective sensitivity “the plant is thus saved from much useless movement, as during a high wind the glands can hardly escape being occasionally brushed by the leaves of surrounding plants.”[iii]

Matt pointing to a sundew and not sliding down the cliff.
I did not stop to poke the sundews.  Nor did I look to see what prey they grasped in their hairs.  I concentrated on staying more or less upright.  Ron, however, did slip a few specimens into a bag.

In total we collect seed from five orchid species:
Platanthera integrilabia     Monkeyface orchid
Platanthera clavellata        Small green wood orchid
Pogonia ophioglossoides    Snakemouth orchid
Calopogon tuberosus         Common grass-pink
Malaxis uniflora                 Green adder’s-mouth orchid

Snakemouth orchid, Pogonia ophioglossoides
The snakemouth orchid (Pogonia ophioglossoides ) and the common grass-pink (Calopogon tuberosus) were especially exciting to find growing in Tallulah Gorge.  Both orchids are common in Georgia’s coastal plains, but this is the only known mountain population of each species.   

The seed can be grown into plants, and then the plants can be placed in mountain bogs that the Atlanta Botanical Garden is restoring.  The ideal is to grow material from the recovery location and return the plants to the original site to augment the natural population.  In the absence of such material, you can at least strive for a kind of genetic authenticity by using plants from the same kinds of locations, in this case mountain locations. As Ron says, “We don’t like to put Okefenokee orchids in mountain bogs, even if they are the same species.” 

“I could stay here all day,” Matt enthused.  No doubt he could, but it was time to start heading out.  

Ron with our guide, Brian Estes of Georgia Power

[i] Chafin, Linda G. Field Guide to the Rare Plants of Georgia. Athens: University of Georgia Press, 2007.  p. 446.
[ii] Chafin, Field Guide p. 434.
[iii] Darwin, Charles R. 1875. Insectivorous Plants. London: John Murray. p. 264

Sunday, October 9, 2011

Field Notes: Hunting for Orchids and Indian Pipe

October 7, 2011
I am riding north with Matt Richards, the Atlanta Botanical Garden’s Conservation Coordinator and orchid specialist.  We are headed to Georgia’s gold country.  It is also orchid country, where both yellow and pink lady’s-slipper flourish, and where the remaining populations of rare orchids species can be found—if you are lucky.  The orchid we are looking for today is Isotria medeoloides, or small whorled pogonia.  The U.S. Forest Services has been monitoring the plant for the past 15 years, and its numbers have been in steady decline.  
Isotria medeoloides in bloom.  Photo: Dennis D. Horn.
Our first stop is a gas station in Suches, which boasts the highest elevation of any Georgia town (just shy of 3,000 feet).  In my experience, fieldwork meet-ups tend to be at gas stations, which is convenient since you get one last visit to the bathroom and a chance to buy water and other provisions before entering the woods.  Deciduous forests aren’t the greatest for finding secluded spots for a bare-bottomed pee, especially if you are with a group that has split up to search for plants. 
We don’t have to wait at the station for long before Mike Broe arrives.  Mike is a Ph.D. student at Ohio State University working on Indian pipe, a kind of mycotrophic ("fungus feeding") plant that has no chlorophyll and spends most of its life underground. Green plants are called “autotrophs” because they are capable of feeding themselves given sun, water and carbon dioxide.  Mycotrophs take advantage of the symbiotic relationship between trees and mycorrhizal fungi.  Mycorrhizal hyphae (fungal threads) enter into the roots of the trees and the trees benefit from the increased surface area of their root system.  The trees absorb more water and minerals, and the fungus receives nutrients from the tree.  Like a little thief, Indian pipe taps into this symbiotic apparatus, reversing the flow of carbon and other nutrients to meet its own needs.

A more common Indian pipe, Monotropa uniflora, also called Ghost plant.
The only time Indian pipe and other mycotrophic plants are visible is when they flower, pushing mushroom-like through the forest duff.  The kind of Indian pipe that interests Mike is Monotropa hypopitys.  Its flower is a pale creamy white, coral pink or red.  On a recent orchid-seed collecting trip, Matt saw populations of very deep red M. hypopitys similar to ones Mike has observed in Maryland and Ohio.  From his studies of the morphology and DNA of the plant, Mike has reason to believe that this southern population may be a distinct species. When he has looked at specimens under a microscope, Mike has seen white hairs around the stile that are not present in M. hypropitys of the north: “The white hairs are very striking against the red, like Santa’s whiskers.”

Matt (right) showing Mike where we are on the map.  Better than leaving breadcrumbs.
The trail Matt leads us down is densely forested with pine and hemlock and overhung with rhododendron, creating the gloomy atmosphere favored by Monotropa.  It isn’t long before we spot the red flower spikes of M. hypopitys—as it is called for now.  After Mike’s work, it may be assigned a new classification.

M. hypopitys in its red glory.
 Mike is delighted at what he sees.

“Need anything else?  You want help finding your way out when you’re done?” Matt asks before we leave him to it.

“No,” Mike replies, “I’m in hypopitys heaven!”

Our next appointment is with Ronnie Ensley, our guide to the area’s Isotria populations.  Ronnie worked for the U.S. Forest Service where his job was to look for federally protected plant species on land slated for logging.  “I was the only one to apply,” Ronnie told me.  “I learned on the job.” 
Matt has great respect for Ronnie.  “There’s a generation gap between guys like Ronnie and me.  He’s gotta be at least 70, and what he knows nobody else does.  When he’s gone, that it.  It’s important to get out there with him and transfer some of that knowledge.”

Our quarry, the orchid Isotria medeoloides.  Can you see it, the light yellow, five-petaled plant in the middle?
Isotria flowered back in May, so we are looking for what remains of the plant, hopefully with seed capsules intact. It’s a small plant and is especially hard to spot in its spent state.  Also, Isotria often grows among wild cucumber, which has a very similar look.  Not every plant flowers, and in a poor growing season, fewer plants come up at all.

The site of our first search for Isotria.
The first location Ronnie takes us to is a lovely little creek-side slope.  After a search we find lots of wild cucumber and only two Isotria, neither of which have seed capsules and don’t look like they ever did.  We also find a three birds orchid, Triphora trianthophora, which bloomed somewhere between July and September.  The flowers last just a few days and are open only from midmorning to midafternoon.  Triphora in bloom is a truly rare sight.

Three birds orchid with seed capsules.
We drive to another spot and park.  Here we put on orange vests since it’s hunting season.  Rifles are banging away in the distance.  We hike into what was once a road, which is now over-grown with shrubs, sapling tulip poplars and baby hemlock.  Ronnie takes a turn off the path and heads into the forest.  How does he know where to turn?  He doesn’t use GPS or look at a map he’s marked.  Matt and I are baffled.  He just walks right up to the spot where he’s seen Istoria in the past. 
After a bit of a search, we find an Isotria with seed capsules intact. 
“You’re gonna decapitate it, aren’t you?” Ronnie asks Matt.  “I can’t watch.”

Our guide, Ronnie Ensley in the foreground.
Matt assures him that he’ll only keep around 10% of the seed.  The rest he’ll disperse in the same spot, some as raw seed and some in prepared packets to bait the fungus Isotria needs to grow.  What Matt keeps he will try to grow in the tissue culture lab back at the garden, and some will simply be stored as back up against extinction. 
At the last site I actually find an Isotria with seed.  I am quite pleased with myself since it is particularly ratty and difficult to see.  I consider myself extremely lucky to be able to come along on fieldwork.  As I see it, my first duty is not to get in the way.  My second is to be a pleasant traveling companion.  I feel especially glad when I can actually be of some use. 

Our last Isotria of the day and my first find.
 We hike back to our vehicles and part ways with Ronnie.  It’s been a good day.  We found what we were looking for—which happens as often as not in Matt’s line of work—and we collected seed. As we motor through the countryside, Matt grips the wheel and exclaims, “There is no way I could have found those plants without Ronnie.”