Pollination of Platanthera ciliaris orchids in the Pisgah National Forest, North Carolina — 2018-07-27

I am not a scientist (in the strict sense), and I don’t play one on TV. But, I do like to observe things in nature and attempt to explain some of the things I see. Case in point: The subject of today’s blog post.

Being a nature photographer often presents me with situations that make me go, “Hmmmmmmmm”. While photographing the beautiful Platanthera ciliaris or Yellow Fringed orchid (more aptly called Orange Fringed orchid), I usually like to take my time and enjoy the moment. At my favorite site for them way back in a secluded part of the Pisgah National Forest, I often see butterflies flitting back and forth on the flowers, frantically working them to retrieve the sweet nectar hidden deep down in each flower’s long nectar tube. This appears to happen more often during the heat of the day around noon, especially on sunny days.

These butterflies will work their way down the roadside, visiting each flower scape along the way. They will then fly back up the road to the beginning of the population of orchids, and make their way back down the road, again. Over and over this happens. If you are patient and sit in front of a particular orchid scape, you will be rewarded by seeing the pollination action over and over again as the butterflies (the same one in many cases) continue to come back for more.

The butterfly in question is Battus philenor or the Pipevine Swallowtail butterfly. These appear to be the workhorses when it comes to pollinating the Yellow Fringed orchid, at least at this site. I did see yellow and black Papilio glaucus or the Eastern Tiger Swallowtail butterflies flitting around, but none of them seemed the least bit interested in the orchids.

Some really botanically geeky stuff follows:

I shall digress a bit here for some background. Larvae of the Pipevine Swallowtail butterfly and those of the other swallowtails belonging to the tribe Troidini feed on plants in the genus Aristolochia (of which the Pipevine or Dutchman’s Pipe is a member), and are commonly referred to as the Aristolochia Swallowtails. But, because “Pipevine” is easier to say than “Aristolochia”, we will call them Pipevine Swallowtails. Here is an informative article from www.gotscience.org about the life-cycle of the Pipevine Swallowtail butterfly.

The following is a shot of one of the strange flowers of the toxic, Aristolochia macrophylla or Dutchman’s Pipe followed by an image of the vine and heart-shaped leaves which the larvae of the Pipevine Swallowtail butterfly feed on. These vines often reach more than 30 feet (9 meters) into the canopy of the forest, and the flowers are almost always toward the top of the vine, making them somewhat difficult to photograph.

Dutchman's Pipe flowerDutchman’s Pipe flower

Dutchman's Pipe vine and leavesDutchman’s Pipe vine and leaves

And now a bit of ‘splaining about the reproductive mechanism of the native orchid, Platanthera ciliaris or Yellow Fringed orchid. As with all other orchid species (it is, in fact, what makes an orchid an orchid), the reproductive parts (male and female) are fused into a structure called the “column”. Here is an image of a Yellow Fringed orchid flower with the pertinent parts labeled:

Yellow Fringed orchid with details

Note the parts labeled “Anther (male) sac”. This is the portion of the column that covers and protects the pollinia until they are manually removed by the pollinator, in this case, the Pipevine Swallowtail butterfly. Here is a crude drawing of a pollinium I made a few years ago:

Drawing of a Platanthera pollinium

Note the coherent pollen grains in the upper portion of the structure. Unlike most other flowers, orchids (as well as Asclepias or Milkweed species) have their pollen stored as waxy, coherent grains. These pollen grains remain compact until the pollinium is removed by a pollinator, at which point, they begin to loosen up and can be transferred to the stigma of the flower as the pollinator brushes against it.

Just how does this work? I’m glad you asked. As the pollinator positions itself on the edge of the flower directly facing the nectary opening, it pushes its proboscis into the opening to retrieve the nectar. The orchid has a sly method to encourage the pollinator to get closer to the anthers where the pollinia are safely stored: it does not fully fill the nectar tube with nectar, thereby forcing the pollinator to get closer and closer to the column as it tries to reach the nectar. When it finally pushes directly against the column, the extremely sticky pads on the ends of the pollinia adhere to the eyes of the pollinator so that when it pulls away to visit another flower, the pollinia are removed from the anther sacs. This sounds a bit gruesome, but the pollinator doesn’t seem to mind. After a period of time, the pollinia will fall from the eyes or be brushed off — they do not remain on the pollinator’s eyes permanently.

In this way, orchids and pollinators have both evolved to benefit each other. The orchid provides nectar for the pollinator and the pollinator facilitates reproduction for the orchid. A win-win situation. This works well from day to day, year to year, but I fear that climate change could wreck this wonderful marriage. You see, if warming occurs too quickly over a short period of time, either of two things might happen: 1. the flowers will bloom earlier than the pollinator hatching, thus having no pollinators when the flowers are in full bloom, or 2. the pollinators will hatch well before the flowers bloom, thus having no orchid flowers to pollinate. In either case, it is definitely a tragic situation for the orchids, not the butterflies. Butterflies have alternative sources for nectar; orchids rely solely on the butterfly pollinator for reproduction. That is to say Yellow Fringed orchids are designed to be pollinated by an insect with large eyes and a long proboscis. Only a butterfly fits this bill…

I have seen bees visit the orchid flowers, on occasion, but they are incapable of pollination. Their proboscis is much too short to reach the nectar through the nectary opening, and their head is too small to span the anthers on the column. I believe that the bees and flies and other insects that visit the flowers are opportunistic and take advantage of the tiny morsel of nectar that the butterfly leaves on the edge of the nectary opening as it pulls its proboscis out of the nectar tube. Otherwise, there is no reason for these other insects to visit the flowers — the loose pollen that bees, in particular, collect from other flowers is just not present with orchid flowers.

Now, to what most of you have been waiting for — the eye candy…

Here is a series of shots of the Yellow Fringed orchid being visited (and pollinated) by the Pipevine swallowtail butterfly. These images were taken over a period of a couple of hours in the Pisgah National Forest in Transylvania County, North Carolina:

Pipevine Swallowtail pollinating the flowers of a Yellow Fringed orchid

This was fairly early on in my visit to this site. Note that there are only a few pollinia attached to its eyes. As time progressed, the butterfly picked up additional pollinia as it visited other orchid flowers along the roadside.

Here is the butterfly back for another visit of the same flower about 15 minutes later. Note the additional pollinia attached to eyes. See if you can spot its tiny “buddy”, a small bee-like critter. It is hovering, head-on, just to the right of the second flower from the bottom right. I saw this tiny critter seemingly follow the butterfly as it made its rounds. It would visit the flowers just after the butterfly retrieved nectar from the flower. I believe it was acting in “clean-up” mode, scouring the edge of the nectary opening for any droplets of nectar that the butterfly had left.

Pollinator (with its buddy) approaching the orchid scape

Here is a close-up of the butterfly with approximately 10 pollinia attached to its large eyes. Those pollinia on the right eye came from the anthers on the right side of the flowers it visited; those on the left eye came from the anthers on the left side of the flowers:

Close up of a butterfly pollinating a Yellow Fringed orchid flower

This is a shot showing the butterfly’s head pushed in as far as it can go so that it can get the last dregs of nectar from the nectar tube. It probably had to go that far in because it got the easy portion on a previous visit. If you look closely, you can see some of the pollinia it picked up from visiting other flowers splayed out on the edges:

Butterfly pushing way into the flower to get the last dregs of nectar

Some additional shots:

Butterfly pollination Butterfly pollination
Butterfly pollination Butterfly pollination

See if you can find Butterfly’s little friend in the image on the upper left. It is very tiny. Check out the fourth flower bud down from the top. It’s perched on the nectary tube. If you are having trouble seeing the details clearly, you can go to my Flickr site where you can enlarge any of the photos found in this blog. Just click on the image, then, when its image page is presented, just click again on the image to enlarge it.

Here is the butterfly getting close, but not completely butted up against the column:

Butterfly polliination

Finally, a shot showing the intense color reflected off of the underside of the butterfly’s hind wing:

Colorful Pipevine Swallowtail butterfly pollination a Yellow Fringed orchid flower

I did take a few shots of the Yellow Fringed orchids without pollinators. Here ares some of the images:

Large Yellow Fringed orchid scape

Thanks to my Florida photographer friend, Chris Evans, who had visited the site earlier in the week with his kids, I was able to find the strange, double-lipped orchid flowers located at the bottom of the scape:

double-lipped orchid flowers double-lipped orchid flowers
Yellow Fringed orchids Yellow Fringed orchids

After finishing with the butterflies and orchids, I made my way back down the mountain to the town of Brevard, North Carolina, where I would have lunch at my favorite Mexican Restaurant, El Chapala. On the way down, however, I rounded a corner of the narrow, gravelled mountain road, and saw what I thought was a stick in the middle of the road. As I neared it, however, I realized it was a snake! And a rather large and fat one, at that! I slammed on the brakes, grabbed my camera, and carefully got out of my truck, hoping not to spook it. Here is what I saw:

Snake in the road

I identified it right off as the yellow phase of a Crotalus horridus or Timber/Canebrake Rattlesnake. And what a beauty! I estimate that it was about 4 feet (1.2 meters) long. I do know that this species is not aggressive in the sense that it would quickly strike at me, unless it was provoked. So, I was able to get fairly close to photograph it. As I neared, though, it did begin to assume a defensive pose and curl back on itself:

Timber/Canebrake Rattlesnake

I knew that it would just rather be left alone and go about its business, so I didn’t want to spend too much time with it. As I was taking another shot, a truck pulled up behind me (I was in the center of the narrow road, blocking it). I turned around and signaled that I was photographing something in the road, and the driver got out of his truck and used his iPhone to photograph it, himself.

One final shot of the Timber/Canebrake Rattlesnake before it decided that it had enough and slithered to the edge of the road, into the woods:

Timber/Canebrake Rattlesnake just before it left the road for the woods

Well, that was special! A bit of excitement that I definitely was not expecting. And I had just been tromping through the roadside weeds photographing orchids and butterflies!!!

I finally made it into Brevard, had my lunch, and headed on back toward home.

On the way back, I stopped along the road to photograph some other Yellow Fringed orchids that I had spotted on my way up into the Pisgah National Forest. There were several dozen plants in a small grouping, in all stages of bloom down in a slight depression just off the edge of the road. They were in a bit of shade, so I decided to photograph them taking advantage of the lack of harsh shadows created by bright sunlight, as was the situation with my previous orchid images. Here is what I found:

Yellow Fringed orchids

In this population, the flowers were more densely arranged on the flower scapes, and some of the flowers had lightly colored fringe on the lip and a bit of white around the dorsal sepal, especially on the flowers in the upper portions of the scape.

Yellow Fringed orchids

Yellow Fringed orchids

Here is a close-up of some of the flowers from the plant in the above image:

Yellow Fringed orchids

What a day of excitement! I finally made it back home and immediately downloaded the images from my camera to see if I had any good ones of the butterflies pollinating the orchid flowers. I’m fairly satisfied with what I got, and I hope you have enjoyed the images and the description of the pollination process.

I really did not expect to make a blog post from this trip, as in the famous John Lennon quote “Life is what happens to you while you’re busy making other plans.” And, as Ines Vieira says in her book, When Life Gets in the Way: “Life doesn’t always see eye to eye with a person’s plans. Sometimes you have to let go if you want to experience the true beauty life is willing to offer you.” So it goes…

Until next time,

–Jim

23 comments


  • Ryan LeBlanc

    Unreal shots Jim….keep up the good work! I especially like the focus on the butterflies!

    July 28, 2018
  • jim

    great photos, what camera and typical f stop, iso?

    July 28, 2018
    • Jim

      Hey Jim, I wish I had a simple answer for you, but it is very complicated. The ISO on these images ranges from 100 to 800 and the f/stop on these images ranges from f/8 to f/18. I had to play around with all of these settings on the fly to get the best results. The amount of sunlight also was a controlling factor. From time to time, clouds darkened the subject a great deal. I tried to keep the shutter speed between 1/1000 second to 1/2000 second to stop the butterfly wing movement. Thanks for the question! The camera is a Sony a7rii with a 90mm lens. –Jim

      July 28, 2018
  • Mary Pat Holtschlag

    Amazing photos!

    July 28, 2018
  • Susan

    Maybe your best photography yet! And fascinating about the pollination… but I do have a question. How does the pollinaria get to the stigma? Does it just get unstuck when the butterfly goes in for the last of the nectar? Thanks Jim.

    July 28, 2018
    • Jim

      Susan, when the pollinia are pulled away from the plant, they are internally structured to always point forward so that when the pollinator faces the next flower, the pollinia will be pointed toward the stigma. Isn’t it amazing? Thanks for the question. –Jim

      July 28, 2018
  • Lucy

    Fascinating Jim! What stupendous pictures!

    July 28, 2018
  • Deynise Lau

    Thanks for the pretty yellow fringed orchid and pipeline butterfly photos. I’ve seen these orchids but they are in places I can’t stop at. The pollen grains on the swallowtail eyes are so interesting!

    July 28, 2018
  • Kathy Gregg

    Wow, gorgeous photos, better than I ever got. I studied pollination of P. ciliaris at Beavers’ Meadow, Barbour County, WV, for several years. There it was pollinated by tiger swallow tails, spicebush swallowtails, and monarchs, in addition to pipevine swallow tails. The most pollinia on a single butterfly I ever caught was 39!!!! What a load for a lightweight butterfly.

    July 28, 2018
  • Joe M.

    Absolutely amazing photos of the orchid and spicebush butterfly and thanks for the science lesson!

    July 28, 2018
  • Katharine Gregg

    Wow, gorgeous photos! I used to study pollination of Platanthera ciliaris at Beavers’ Meadow in Barbour County, WV, back in the 1980’s. In addition to pipevine swallow tails, they were pollinated there by tiger swallowtails, spicebush swallowtails, and monarchs. The most pollinia I ever saw on a butterfly I caught was 39!!! What a load for a lightweight butterfly! Here are more details about pollination, which Charles Darwin wrote about in his 1862 book titled “On the various contrivances by which British and foreign orchids are fertilised by insects.” The two pollinia are placed on the butterfly’s eyes, one on each side. At that time the pollinia are pointing outward at an wide angle. But after a bit of time passes, the two pollinia move toward each other until they are almost touching. Then when the butterfly lands on another flower and sticks its proboscis down into the nectary tube, the pollinia are right in front and touch the sticky stigmatic fluid in the center of the flower just above the nectary opening. Now, unlike most orchids, the pollen in Platanthera pollinia is amassed into a mealy mass. When a pollen mass touches the stigma, a group of pollen grains is left but not the entire pollinial mass. That way, a butterfly can pollinate many flowers with the same pollinia until all the mealy pollen is gone. Cute, huh?

    July 28, 2018
  • Katharine Gregg

    Wow, what gorgeous photos! I studied the pollination of Platanthera ciliaris in Beavers’ Meadow, Barbour County, WV, back in the 1980’s. In addition to the pipevine swallowtail, there they were also pollinated by tiger swallowtails, Eastern black swallowtails, spicebush swallowtails, and monarchs. The most pollinia I ever saw on a butterfly I collected was 39! What a load for a lightweight butterfly!
    Charles Darwin described the pollination of Platanthera in his 1862 book titled, On the various contrivances by which British and foreign orchids are fertilised by insects.” Here are the details. When a butterfly sticks its proboscis deep into the nectary tube, it touches the sticky pads on the ends of each of two pollinia and they get stuck one on each compound eye. At that time they are facing away from each other at a wide angle. After a bit of time, the two pollinia move toward each other until they almost touch. In that way, when the butterfly visits the next flower, the two pollinia will be pointing right at the central, glistening sticky sigmatic surface just above the entrance to the nectary tube. And that’s not the end of the story! Platanthera orchids are unusual in that their pollen is loosely massed into mealy wads of pollen instead of the hard, waxy pollinia in most orchids. Consequently, when a pollinium touches the stigmatic surface, only a group of pollen grains will be left behind, leaving the rest to be deposited on another flower. Thus, a butterfly can pollinate many flowers with the same two pollinia!

    July 28, 2018
  • Steve Pyne

    Wow Jim! These are truly amazing pictures! And what a great post! Missing you here at the NOC, but it is obvious that you are keeping yourself well occupied. Thanks for for this post and all the others!

    July 28, 2018
  • Shelley

    Beautiful photos— thanks. I would love to see any close-up shots you have of milkweed.

    July 28, 2018
  • Great set of photos and pleasing to read after the trouble you took to explain.Well done Jim.I particular led the first and last shots, pin sharp and nice colour combination.

    July 29, 2018
  • Adair Pickard

    Jim, the photos are beautiful. I especially appreciate the information you offer. Beauty and education in one packet and I come away feeling renewed. Thanks

    July 29, 2018
  • Margie Anderton

    I have a dutchman pipe vine on a trellis and get to enjoy the many swallowtail caterpillars devouring it! Sometimes there are so many on it you can stand 5 ft away and hear them chewing! Needless to say I don’t have leaves on it but a few days out of the year! As soon as it puts out new growth it is gone!

    July 29, 2018
  • Robert Curry

    Thanks again Jim for the wonderful photos and biology lesson. The Canebrake is a remarkable specimen and, probably, you save its life and educated the truck driver about such magnificent animals.

    July 29, 2018
  • Absolutely marvelous! I so enjoyed your photos of the pipevine swallowtail pollinating this orchid from a previous year, and I remember you granting me permission to use them in my artwork, for which I’m very grateful. It’s great to see even more photos of this fascinating process. For a photo of the artwork I produced, see: https://mazastudio.blogspot.com/2017/03/yellow-fringed-orchid-and-pollinator.html

    July 29, 2018
    • Jim

      Thanks, Elena.

      As usual, your artwork is delightful as well as technically accurate. I appreciate your giving me photographer credit.

      Best, Jim

      July 29, 2018
  • J. Dan Pittillo

    Jim, You do a beautiful observational photography. You, in your own right, are a scientist. You are adding knowledge even if not a complete story as in this one at Univ. of Florida.

    http://entnemdept.ufl.edu/creatures/bfly/pipevine_swallowtail.htm

    I have a transplanted pipevine in my wildflower garden (Nodding Trillium Garden) and watched a Battus philenor female searching for the plant to lay eggs on. The vine was lying flat on the ground and she appeared to lay eggs there and proceeded for next several minutes searching other plants. None fitted the need. Finally she stopped and spread her wings resting and I left.

    My question: I wonder if they also get up in the trees for other leaves or hunt just on the ground. Maybe someone with this observational experience will respond.

    July 29, 2018
  • Bonaventure Magrys

    Beautiful photography Jim! Have you yet found a peloric Platanthera? In some photos the pedals looked almost fringed like the lip.

    July 30, 2018
  • Valerie Bourdot

    Beautiful, amazing and thank you!

    August 08, 2018

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