#platanthera cristata

[indefenseofplants]

An Orchid of Hybrid Origin

Hybridization is an often overlooked mechanism for evolution. We are taught in high school that hybrids such as mules and ligers are one-off's, evolutionary dead ends doomed to a life of sterility. Certainly this holds true in many instances. Species separated by great lengths of time and space are simply incompatible. However, there are instances throughout the various kingdoms of life in which hybrids do turn out viable.

If they are different enough from either parent, their creation may lead to speciation down the line. Such events have been found in ferns, butterflies, and even birds. One particular example of a hybrid species only recently came to my attention. While touring the Atlanta Botanical Garden I came across a fenced off bed of plants. Inside the fence were orchids standing about knee height. At the top of each plant was a brilliant spike of orange flowers. "Ah," I exclaimed, "the orange fringed orchid!" The reply I got was unexpected - "Sort of."

What I had stumbled across was neither the orange fringed orchid (Platanthera ciliaris) nor the crested yellow orchid (Platanthera cristata). What I was looking at were a small handful of the globally imperiled Chapman's fringed orchid (Platanthera chapmanii). Though there is some debate about the origins of this species, many believe it to be a naturally occurring hybrid of the other two. In many ways it is a perfect intermediate. Despite its possible hybrid origins, it nonetheless produces viable seed. What's more, it readily hybridizes with both parental species as well as a handful of other Platanthera with which it sometimes shares habitat.

Despite occasionally being found along wet roadside ditches, this species is rapidly losing ground. The wet meadows and pine savannas it prefers are all too quickly being leveled for housing and other forms of development. Although it once ranged from southeast Texas to northern Florida, and southeast Georgia, it has since been reduced to less than 1000 individuals scattered among these three states.

There is a light at the end of the tunnel though. Many efforts are being put forth to protect and conserve this lovely orchid. Greenhouse propagation in places like the Atlanta Botanical Garden are helping supplement wild populations while at the same time, maintaining genetic diversity. New populations have been located in Georgia and are now under protection. Though not out of the woods yet, this species serves as a reminder that a little bit of effort can go a long way.

Further Reading: [1] [2] [3] [4]

[cedar-glade]

Platanthera ciliaris

Yellow fringed orchid

Any way you go about looking at this species, full anthesis or not, it becomes clear why people drive out of there way to see them once a year. This orchid, although considered one of the bog orchids, can tolerate a number of xeric conditions as long as an aerated ericaceous soil with correct mycorrohizal groups are present.  It can be found in sedge meadows, marshes, wet sandy barrens, mixed ph barrens(like this one), moist open woods, wet meadows, prairies, and deep humus of upland Eastern Oak Hickory forests at steep hills edge or cliffs edge.  It usually requires some form of disturbance to keep its habitat in check and in most of these areas that means fire dependency to recreate open growing conditions. Currently, although tree species never get big enough in the barren that these photos were taken at, the management has done prescribed burns to mitigate woodies. In the wetter sections of sand barrens fire and sandblasting are associated with preservation of habitat. 

As you may already know, many of the issues involving the development of this species habitat is the major reason for it’s decline. Habitat connectivity is effected constantly by agricultural systems and the use of herbicides in places that may have seen colonies. Other issues involve the destruction of thicket and subthicket food sources for larval stages of large butterflies, specifically the swallowtails, that if not addressed could lead to enough population numbers for a few plant species to potentially go extinct. Although any species feeding on paw paw may be stable as well as species feeding on spicebush/sassafras maybe stable, we have seen the major decline of those species feeding on pipevines, golden alexanders, sub thicket Spirea spp., and the citrus false ashes(wafer/prickly), which is directly associated to the low numbers of those plants in natural landscapes. Both Lillium spp. and many fringed orchid species, despite local abundance in some cases, fail to get pollinated enough to see a real comeback. Although hawkmoths and hummingbirds visit these plants for the nectar at the back of their long orange nectar spur, size/shape and how the would be pollinator positions it’s self on the flower matters to the specific format necessary for pollination. 

The flowers form on a pinwheel raceme, pinwheel seen in the right most photo, blooming from the bottom to the top. The butterflies that seem to visit and properly transfer pollinia have to extend their proboscis far enough down the nectar spur to the point that they too may come in contact with the stigmatic surface and also pop the anther cap and receive the pollinia onto it’s head. Some studies, such as the study of a certain P. ciliaris population’s ecology in a southwestern Michigan bog, (Smith and Snow (1976) ), seems to suggest that the most likely candidate for this would be spice bush swallowtail. Though this and a few other similar studies may not have taken in the concepts associated with local numbers of other swallow tail species being lower due to lack of larval food. 

Other issues with this species involve new/usable habitat loss. In what could of been decent habitat if fire regimes were applied and if left undisturbed by the backhoes, trench sifters, and breaker bars once established are the ditches of grazing/ horse pastures with low amounts of invasive grasses/shrubs/ect. in the area. Connectivity of runoff ditches near the sides of road seem to serve their function in offering footholds to this species as long as the basic ericaceous soil requirements are met with the lack of herbicides fungicides and pesticides. (I will post a ditch image and a pasture/ sedge meadow as an example tomorrow. ) Aside from that issue, poaching is always an issue for these orchid species. People dig them up and sell them, most people trample an area of the single leaf, compact the soil, and even break blooming sized species( multiple leaf with spike). Damaging these species in anyway can cause them issues down the line and will set them back years. In some cases they may even revert to their protocorm stage or die( Case, F. W. 1987. Orchids of the Western Great Lakes Region. ) If you are attempting a rescue from a field or ditch that you know will be destroyed, contact your DNR. It’s best to just admire them and study them from a distance though if that is not the case. It is illegal to move them across state lines during any rescue without proper permits. 

That aside, there was a time period when the eastern USA saw these and many other species as abundant. Before the agricultural development and death/displacement of many tribes there were periods when they could be used... when this species was common in wet depressions a few different tribes used this to treat many issues, from headaches and bowel issues to inflammation and snake bites and was considered an important resource for those tribes.

In those early days it was also possible to see a few look-a-likes P. Xbicolor (P. ciliaris x P. blephariglottis), which is a variegated white/orange long labellum species, and the crested orange fringed orchid, P. cristata, which has smaller labellum and nectar spur than the orange fringed orchid, P. cilliaris.

If you are interested about the location where I took these photos, I made a post yesterday explaining what HD Meadow was.