Deep Woods Field Trip
Deep Woods, the Appalachian Gametophyte, and Ohio Geobotany
Substrate-associated plants: For our field trip this week, we took a trip down south to the unglaciated region of Ohio. This area is dominated by acid sandstones, and therefore has lots of plants that are only found in these drier areas. One of the first examples we saw was chestnut oak (Quercus montana). This species of tree in particular is known to have silvery-white bark. It is also a quickly growing tree and can grow up to 60 feet tall! Chestnut oaks are also commonly used by landscapers due to its ability to sustain itself in poor quality soils and provide shade. Lastly, the bark of chestnut oaks typically has high levels of tannin, similar to red oaks.
The lobes of chestnut oak are usually more round, helping to distinguish it from chinkapin oak.
Another example that we saw growing throughout the Hocking Hills area was rough leaf goldenrod (Solidago rugosa). This plant typically grows in well-drained soils that are slightly acidic, so it was a prominent species found throughout our field trip, especially in the wetland area we briefly visited. One really cool fact about rough-leaf goldenrod and other species of goldenrod is that they have some incredible medicinal uses. The flowers are often used to reduce inflammation, help with sore throats, and improve urinary health. They also contain antioxidants and can be used in herbal supplements and teas.
The goldenrod flowers are a great example of a plant in the Asteraceae family!
Over the course of our visit to Deep Woods, we were able to observe several different species of ferns! One of my favorites ones that we saw was a sensitive fern (Onoclea sensibilis). This type of fern in particular prefers shady areas that have soil that is moist, well drained, and is slightly acidic. This species of fern is an example of having fronds that are dimorphic. This means that the sterile and fertile fronds have physical differences, which can help in identifying the species. The sterile fronds are more triangular, have a yellow-greenish color to them, and die back once it begins to frost. The fertile fronds, which have the sporangia, are shorter and will persist through winter. This was such a cool fact to learn about and something I didn’t have any knowledge on before!
The difference in fronds play a key role in the life cycle of this fern!
Lastly, to wrap up the substrate-associated plants, we were lucky enough to observe Juglans cinerea, which is commonly known as butternut or white walnut. The leaves of this tree are alternate and pinnate and can often be a brighter and yellower green than other trees. The nuts produced by this tree are eaten by humans and are typically more valuable than any of its wood. This tree is slow-growing and usually has a lifespan of less than 75 years. Some of this is due to butternut canker, a fungal disease impacting this species. The cankers appear sunken and black and work to cut off nutrients and water, causing the tree to eventually die.
We were lucky to be able to find a white walnut tree on our field trip!
Biotic threats to Forest Health: One of the trees we observed on our trip was an American chestnut (Castanea dentata). We also briefly talked about how this tree has been negatively impacted by chestnut blight. This is a canker disease caused by a pathogen called Cryphonectria parasitica. This pathogen can be found all throughout the native range of American chestnut, making it an easy target to be completely wiped out. The pathogen, native to China, can be dispersed by rain or animals such as insects and birds and is also impacting American chestnut trees in Europe. One of the management approaches to alleviate chestnut blight has been to quarantine and isolate chestnuts from eastern states, but that has been difficult due to the wide distribution of the pathogen. Another option is to breed for resistance, which can be seen in the Chinese chestnut. This species has been shown to slow down the progression of cankers, but not get rid of them completely, and the quality of the tree species has decreased.
Eastern hemlock (Tsuga canadensis) was another species we observed that is currently being impacted by the hemlock wooly adelgid (Adelges tsugae). This is a non-native and invasive insect that was introduced by accident from Japan in the 1960s. Since then, it has rapidly caused high mortality rates of eastern hemlock across the United States. When this species of adelgid feeds on eastern hemlocks, it disrupts the use of necessary nutrients causing needle drop, dieback, and mortality. There have been efforts by the Forest Service in an attempt to alleviate this threat. One of the approaches has been biological control. Various species of predatory beetles started being released in 1999 because they feed off this species of adelgid and have worked to try and control population sizes. The use of insecticides that specifically impact the hemlock wooly adelgid has been seen, but only in large areas that are of high ecological or economical value. Lastly, another attempt has been made through silvicultural practices and restoring areas that have been impacted. Interestingly, eastern white pine is similar ecologically, but it isn’t impacted by this insect, so it has been planted in areas most affected by the insect.
Appalachian Gametophyte: On our trip to the Hocking Hills area, we were lucky enough to be able to see the Appalachian gametophyte (Vittaria appalachiana) in one of the rock structures there! This species of plant has some really fascinating natural history as explained by Pinson and Schuettpelz in the article “Unraveling the origin of the Appalachian gametophyte.” One of the main reasons this species is so remarkable is that it “exists exclusively as a vegetatively reproducing gametophyte.” This isn’t characteristic of ferns because they typically are dominated by the sporophyte stage in their life cycle. In fact, only three species of ferns, one being V. appalachiana, are known to have no mature sporophytes.
One of the reasons why dispersal of this species is limited is due to the large size of fern gemmae. They are too large for wind dispersal over long distances. Instead, agents of dispersal over short distances include wind, water, and some animals, such as slugs, which was proven by Kimmerer and Young in 1995.
As stated above, the dispersal capabilities of the Appalachian gametophyte are limited. Based on the evidence collected throughout this study, there is an absence of the species from any area that is north of the “last glacial maximum”. This suggests that the sporophyte that was responsible for the current distribution of Appalachian gametophyte became extinct during the Pleistocene glaciations. As a result, gametophytes lost the ability to produce sporophytes during that last ice age period.
Overall, it was determined that the Appalachian gametophyte is reproductively isolated. There is an abrupt stop of the range of this species into the southern part of New York, which indicates that this species could not be sustained by long distance dispersal from a tropical sporophyte source. Even in areas where V. appalachiana has the right conditions to grow, it remains uncolonized due to the specific sporophyte responsible for dispersal being extinct.
Here’s some Appalachian gametophyte tucked into the crevices of a cave!
Flowers growing in the axils: My specific assignment for this field trip was to find two examples of flowers growing in the axils. One of the first examples that I found was false nettle (Boehmeria cylindrica). This species of plant is characterized by opposite leaves that are coarsely serrated and have small green flowers growing along the leaf axils. Unlike other species in the nettle family, this plant does not have stinging hairs, hence the common name of false nettle. This species is also known to support the larvae of several different butterfly species, most notably the red admiral. Also, in Central America, false nettle is grown as a fiber plant that can be used to contribute to cloth and paper products.
False nettle has several small flowers growing in the area where the leaves and stem meet!
Another example that I found to fit this specific assignment was the sensitive partridge pea (Chamaecrista nictitans). This plant has pinnately compound leaves that tend to fold together when touched, relating back to its common name. It also has small yellow flowers that grow on short pedicels along the leaf axils. Similar to other species in the pea family, it has the ability to fix nitrogen and improve the quality of soil. This species of plant in particular has invasive qualities such as its ability to grow in a wide variety of environmental conditions and naturalize, weedy growth, and good seed dispersal. However, there is not much evidence that it has adverse impacts on surrounding natural vegetation. Along with this, its pollen is useful for several different species of bees.
The sensitive partridge pea plant is a great example of having axial flowers!
Other observations: One of the really neat species that we observed in Deep Woods was a parasitic plant called beechdrops (Epifagus virginiana). This plant grows on the roots of American beech trees and is how it obtains nutrients since it does not possess any chlorophyll. There isn’t a lot of information known about interactions with animals, however some early research shows that the small bilateral flowers of beechdrops are pollinated by bees. Based on some plant historians, it has been predicted that Native Americans made bitter tea by brewing beechdrops flowers, however it is not recommended to consume them today.
This parasitic plant could easily be overlooked on the forest floor if one wasn’t keeping a close eye out for it.
Due to the geology and soil conditions of Deep Woods, we were able to see and identify several different species of mosses. One of my favorites was the haircap moss (Polytrichum commune). This moss can best be described as having little heads of green spikes that look almost like fireworks. One of the neat things I learned is that this is one of the most commonly found plants across the world as it grows natively on almost every continent. Along with this, haircap moss has been used on New Zealand Maori cloaks. It was often woven into the fabric in order to provide some extra insulation and decoration.
This moss has cool little green tufts in all directions!
We also had an example of a scratch-and-sniff plant which was the black birch (Betula lenta). This tree has simple, alternate leaves with serrated margins and are elliptical in shape. When the branches of this tree are scratched, there is a minty smell that can be noticed, which is really cool! Various parts of the black birch tree are used today. First of all, the wintergreen essential oil that contributes to its aromatic scent is used for several purposes such as being antibacterial and antiviral. It is still distilled from black birch trees, but it’s now less common with more synthetic oil products. Also, black birch has very hard wood which is valuable in furniture and cabinets. Lastly, the pulp of black birch is commonly used in paper products such as newspapers and paper towels.
Definitely stop to smell this tree if you stumble upon it in the woods!
While we were visiting Deep Woods, we also had the opportunity to talk about some of the invasive plant species found in this area. One of the examples we observed was wintercreeper (Euonymus fortunei). This is an invasive vine with origins in China and Japan and was introduced to the United States as an ornamental groundcover. This plant has been known to grow in a variety of environmental conditions and invade forest openings. It can grow across forest floors, disrupting native plants as well as climb up tree bark into canopy openings. The best way to prevent and control the spread of this species is to simply not plant it. There have also been efforts to hand pull wintercreeper in areas that have been impacted by its presence and use the application of herbicides.
This invasive vine can cause problems all throughout forest ecosystems.