Flora of a Fen in June

Today I am sharing some photos of plants in bloom taken in a fen in Shannon County, MO. These plants were blooming in June and the combination of high temps, direct sunlight and high humidity made for challenging conditions to photograph indeed. The first subject is Pogonia ophioglossoides, the snakemouth orchid or rose pogonia. These were blooming in abundance at the fen but finding one in the peak of its beauty was the challenge.

As fantastic as it was, I found being in these fens to be quite stressful. First of all, you are typically forced to work in dangerous heat indexes. My friend, David Seidensticker and I made a visit to these fens during our birthday weekend and dreaded leaving the sanctuary of what little shade we could find and use as a base of our operations. If you visit these locations in the summer, be prepared by drinking as much water as you can before you get there and bring plenty of water with you. You really need to constantly drink as you are sweating profusely, losing water at nearly the same rate you can take it in.

In addition to the off-the-chart heat index values, one must carefully select every footstep. This is not only due to the rare plants in bloom, but also because of the soil substrate that forms the base of these endangered fen ecosystems. These fens are comprised of two primary soil substrate types, marly soils and peat soils.

Marly soils are composed mostly of carbonates such as calcite and calcium or magnesium carbonate that precipitate out of ground water. These soils take thousands of years to develop and the typically high levels of magnesium create conditions that only the best adapted floras can survive.

Peat soils are comprised of partially decomposed plant materials that also build up over thousands of years. These soils can typically support more plant species and heavier vegetation loads. Care must be taken to avoid walking much on these soils as our footsteps will not only disturb the plants growing here, but will also act to compress the soil, expelling the gasses trapped and water-logging the root environments.

The best places to walk in these fen types are on the rivulets that run within these fens. Continuously flowing waters have moved most of the soils from these areas to leave a pea-gravel type substrate with gently moving water on top. Plants will still grow within these areas but finding a safe place to put your foot is typically pretty easy.

We found Spiranthes lucida growing at the edges of shallow peat soils next to these rivulets within the fen. Likely the easiest Spiranthes to identify in the state, this is the only Spiranthes species that blooms in spring, has a yellow lip and has an easy to identify growth habit with broad basal leaves that are present when the orchid is in bloom.

Calopogon tuberosus was just beginning to bloom in early June. This orchid is famous for its non-resupinate flowers, meaning that the flowers are not turned 180 degrees, as they are in most orchids. The lip of the flower is found on the upper side of the flower. This species also does not produce nectar or pollen as rewards for would-be pollinators, but uses visual subterfuge to entice insects to land. I found it interesting that Homoya, 1993, suggests that the reason C. tuberosa exists in space and flowering time with P. ophioglossoides (see above) is that the later does provide ample nectar rewards, thereby increasing the chances that a pollinator might land on the similarly colored C. tuberosa flowers.

Justicia americana is a gorgeous member of the Acanthaceae family that we found growing in early June. These plants were most likely to be found growing alone or in small groups along the gravel bottoms of the rivulets within the fen. They, like all of the plants shown here, are not strictly linked to fens per se, but fens do make a nice home for them.

This has just been a small look inside these glorious fens. I hope to continue visiting at other times of year to see other plants in bloom.

Thanks for the visit.
-OZB

REFERENCES

Much of the information from the above was taken from the following sources. I do recommend them both for learning more about the orchids that can be found in fens and anywhere in Missouri.

Homoya, M.A. Orchids of Indiana. Indiana University Press, Indianapolis, Indiana, USA. 1993.

Summers, Bill. Missouir Orchids. Missouri Department of Conservation Natural History Series, No. 1. 1981.