In Search of the Orange Fringed Orchid

In Defense of Plants is finally back for another exciting botanical adventure! This week we explore another wonderful sand prairie in search of one of North America's most stunning terrestrial orchids - the orange fringed orchid (Platanthera ciliaris). Along the way, we meet a handful of great native plant species that are at home in these sandy soils.

Music by: 
Artist: Eyes Behind the Veil
Track: Folding Chair
Album: Besides
https://eyesbehindtheveil.bandcamp.com/

Fall Leaves of the Putty-Root Orchid

Whereas most plants here in the Northern Hemisphere have largely geared down for the long winter, there is one species that has only recently begun a new stage of growth. Though it may seem damaging to produce leaves when a hard frost is just around the corner, that is exactly what this plant is doing. What's even more bizarre is that the plant in question is an orchid.

The putty-rood orchid (Aplectrum hyemale) may seem strange to most. Though it flowers during the same time as most of our terrestrial orchids (May through June), its display can be hard to track down. In fact, lacking any knowledge of a specific location, it is more likely that you will stumble across one before you pick it out of the hustle and bustle on the forest floor.

Flowering occurs at a different time than leaf out. The solitary flower stalk gives way to a single leaf starting in late summer or early fall. Why the heck would this plant start its photosynthetic lifecycle when everything else is about ready to go dormant? The answer is competition. Summer is not a bright season for those growing on the forest floor. This is especially true for a plant that only produces a single leaf.

What the putty-root is doing with its oddly timed leaf production is taking advantage of a dormant canopy. With trees and herbaceous leaves out of the way, the putty-root is able to soak up as much sun as it can get. This is a similar strategy adopted by spring ephemerals around the globe. But what does the plant have to gain from having leaves in the fall? Why not wait until spring to leaf out?

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As it turns out, it simply doesn't have to. The photosynthetic machinery within the leaves of the putty-root perform exceptionally well at low temperatures. Whereas most plants simply can't photosynthesize when it starts getting too cold, the putty-root is able to photosynthesize at temperatures as low as 2° C (35.6° F)! Not only does this enable the plant to get a jump start come spring, its also able to make food throughout most of fall and even early winter.

There does seem to be a limit to this. Once temperatures drop below 2° C, the machinery can't keep up and photosynthesis grinds to a halt. This is further complicated by the fact that the leaves are often buried under snow for months at a time. Certainly its mycorrhizal associations help feed the plant, even when it isn’t actively photosynthesizing. Regardless, this strategy is a great way of getting an extra kick while everything else is slowing down. Stories such as this bring to mind the story of the tortoise and the hare. Sometimes slow and steady really does win the race!

Photo Credit: Lance Merry (www.lancemerry.com)

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

On Orchids and Fungi

It is no secret that orchids absolutely need fungi. Fungi not only initiate germination of their nearly microscopic seeds, the mycorrhizal relationships they form supplies the fuel needed for seedling development. These mycorrhizal fungi also continue to keep adult orchids alive throughout their lifetime. In other words, without mycorrhizal fungi there are no orchids. Preserving orchids goes far beyond preserving the plant. Despite the importance of these below-ground partners, the requirements of many mycorrhizal fungi are poorly understood.

Researchers from the Smithsonian Environmental Research Center have recently shone some light on the needs of these fungi. Their findings highlight an important concept in ecology - conservation of the system, not just the organism. Their results clearly indicate that orchid conservation requires old, intact forests.

Their experiment was beautifully designed. They added seeds and host fungi to dozens of plots in both young (50 - 70 years old) and old (120-150 years old) forests. They continued to monitor the progress of the seeds over a period of 4 years. Orchid seeds only germinated in plots where their host fungi were added. This, of course, was not very surprising.

The most interesting data they collected was data on fungal performance. As it turns out, the host fungi displayed a marked preference for older forests. In fact, the fungi were 12 times more abundant in these plots. They were even growing in areas where the researchers had not added them. What's more, fungal species were more diverse in older forests.

The researchers also noted that host fungi grew better and were more diverse in plots where rotting wood was added. This is because many mycorrhizal fungi are primarily wood decomposers. Nutrients from the decomposition of this wood are then channeled to growing orchids (as well as countless other plant species) in return for carbohydrates from photosynthesis. It is a wonderful system that functions at its best in mature forests.

This research highlights the need to protect and preserve old growth forests more than ever. Replanting forests is wonderful but it may be centuries before these forests can ever support such a diversity of life. Also, this stands as a stark reminder of the importance of soil conservation. Less obvious to most is the importance of decomposition. Without dead plant material, such fungal communities would have nothing to eat. Clearing a forest of dead wood can be just as detrimental in the long run as clearing it of living trees.

Research like this is made possible by the support of organizations such as the Native North American Orchid Conservation Center. Head on over to www.indefenseofplants.com/shop and pick up an In Defense of Plants sticker. Part of the proceeds are donated to this wonderful organization, which helps support research such as this! As this research highlights: What is good for orchids is good for the ecosystem.

Further Reading:

http://onlinelibrary.wiley.com/doi/10.1111/j.1365-294X.2012.05468.x/abstract;jsessionid=3385C965FF5BA4CB83290005DFD47FD1.f01t02