1. Substrate-associated Plants

  1. Sourwood, Oxydendrum arboretum, is a plant endemic to North America. It doesn’t show up on other continents unless it’s introduced, and it has no closely related species. The leaves of the sourwood are, as the name suggests, sour and bitter to taste, but historically, tea made from its leaves is a favorite of mountain-climbers and naturalists for its rejuvenating properties. It was extremely useful to pioneers, who would use the sap in a fever-reducing medicine; the bark to soothe mouth pain; and tea from the leaves to treat everything from indigestion to dysentery (source).

    Oxydendrum arboretum

  2. Chestnut oak, Quercus montana, is unique in its ability to survive on steep, rocky slopes where other oaks cannot, such as the terrain we saw in southeastern Ohio. It has a tap root system, and this system makes it extremely sturdy and adaptable to conditions other oaks find unfavorable. The acorns that a chestnut oak produces are a staple for wildlife, including rodents and birds alike. The tallest chestnut oak to date is in Tennessee, in Great Smoky Mts National Park, standing at 144 feet tall! (source)
  3. Scrub pine, Pinus virginiana, also called the spruce pine and Virginia pine, is found commonly in old growth at high elevations. It likes to grow in pure stands (with members of its own species) rather than in mixed groups. Small compared to other pines, with a maximum height of only 40ft, it grows wide and pyramidal. It prefers full sun with well-drained, sandy acidic loam, which is in abundance in places like southeast Ohio. In fact, it prefers to grow in poor, dry soils, making it a staple in places like Hocking Hills (source).
  4. Pitch pine, Pinus rigida, is not the traditional shape when one pictures a pine tree. It has an irregular twisting form, with gnarled, uneven, even drooping branches. As it gets older, the needles will turn a dark green and the bark grows almost black. Currently, pitch pine is a popular lumber and pulpwood tree, but colonists used to use the resin to produce turpentine and tar. Knots taken from this tree burned slow, and thus were used for torch heads. It thrives in dry rocky soil that other trees cannot tolerate. It is resistant to both fire and injury, with both the roots and stumps able and willing to produce new sprouts (source).


2. Biotic Threats to Forest Health

  1. The biggest biotic threat to the American chestnut (Castanea dentata) is the pathogen Cryphonectria parasitica, the cause of chestnut blight. The American chestnut is a huge tree with a wide, straight stem, making it easy for lumber. The wood is almost ideal for crafting; it’s extremely sturdy, very durable, and, best of all, extremely common with roots that will regenerate by themselves. Chestnut blight is a canker disease that affects every part of the plant, at any size–branches, stems, shoots, and leaves–and can enter the tree through even the smallest of wounds. The cankers grow rapidly to kill the tree from the inside out, and continue to colonize and, for lack of a better word, consume the tree even after it’s died. The Chinese chestnut (Castanea mollissima) is almost completely resistant to chestnut blight, and in a desperate effort to save the American chestnut, work is being done to create an American-Chinese hybrid that is hopefully able to stand up to the pathogen (source).

    A chestnut leaf extremely affected by chestnut blight.

  2. The hemlock woolly adelgid (HWA) is an invasive, aphid-like insect that is the main threat to North American hemlocks, especially the eastern hemlock (Tsuga canadensis). The bugs are extremely small, but are easy to see when they form huge white groups on tree branches, making the tree look almost fuzzy. They feed on the tree’s stored starches, disrupting the flow of nutrients to other twigs and needles. A horde of them can kill a tree anywhere within 4 to 10 years. Hemlocks are well-suited for growing on steep slopes, and their extensive root systems help stabilize shallow soils for erosion control. They create heavy shade and are crucial for species that thrive in the dark, sheltered environments stands of hemlocks create. To help control the HWA, one of the management tactics has been to attempt releasing predators, other insects native to Asia, where the HWA originates, with mixed success. Chemical insecticides can be used to treat an already-infested tree, but this is most effective on an individual basis, and is not practical in a forest setting (source).

    From the understory of an eastern hemlock stand, not yet haven been taken over by the HWA.


3. Appalachian Gametophyte

The Appalachian gametophyte, Vittaria appalachiana, is unique in that even as a ‘mature’ plant, there have never been mature sporophytes observed – it appears to stay in the gametophyte stage for the entirety of its life. Instead of spores like most other ferns (in fact, only three ferns including the Appalachian gametophyte have  never had mature sporophytes observed), it reproduces asexually by the production of gemmae, which are dispersed short distances by wind, water, and small animals and insects like ants.

Gemmae are large compared directly to spores, typically anywhere from 0.2mm-1.0mm in length, which is generally considered too large for the wind to carry long-term (unlike spores, which are only moved by wind-dispersal). The notion of limited dispersal is supported by the absence of this species existing outside of a narrow range within the last glacial movement. Even recently disturbed sites (like roads) that are within the range of V. appalachiana are rarely colonized, despite it existing on a very similar surface nearby. Taken together, these two data sets encourage the idea that while V. appalachiana might have produced spores at one point, they don’t anymore, as they might have found a more effective way to propagate.

There is a possibility that current populations of V. appalachiana are being sustained by long-distance dispersal, likely by some tropical sporophyte source, but it can be rejected almost immediately based on allozyme studies, as well as its extremely narrow range. Current distribution would be due almost exclusively to spore dispersal, with the sporophyte becoming extinct before or during the last glaciacion in the Pleistocene. The gametophyte also displays an apparent inability to extend north, past the boundary of the last glacial movement.

In short, no, it’s almost impossible to say that the Appalachian gametophyte is being distributed and sustained by movement of spores, when things such as allozyme and current and expanding range are all taken into account (source).

4. Misc. Observations

  1. Reindeer lichen, Cladonia rangiferina, is hardly a plant at all. As a lichen, it is formed by the symbiosis of one or two species of fungi in correlation with a photosynthetic alga. It is most common in the circumpolar north, where it provides an abundant food source for animals like reindeer (so, quite aptly named). It was used by Scandinavians for a variety of things, from food in soup and dessert, to filling for huts and insulation, to decoration. It is actually the most popular lichen for use in miniature trees in model architecture and trains! In 2014, students in Sweden discovered that the lichen has an amazing capacity to absorb and deaden sound, which lead to the creation of sound absorbers being used worldwide, crafted from reindeer lichen (source).
  2. Pinesap, Monotropa hypopitys, is a parasitic plant that uses fungi to obtain carbon from the root systems of autotrophs. It does not perform photosynthesis, instead getting its nourishment from the fungi stealing from roots, most often afflicting oaks and pines. They prefer acidic soil, likely part of the reason they target oaks and pines that are most common on in the acidic forests of southeast Ohio (source). Since they don’t photosynthesize, their leaves are non-functional and have basically devolved down to loose, scale-like appendages along the stem, the same color as the flowers. The relationship it holds with the fungi, being fungi-dependent (without the fungi it will not survive), is defined as mycotropism (source).

    Pinesap sporting a distinctive red color.

  3. Japanese stiltgrass, Microstegium vimineum, is an invasive species that was brought over presumably accidentally in shipments to North America from Asia, and it has spread like wildfire through all fifty states. They are notorious for their ability to multiply and then crowd out native organisms, essentially creating a monopoly on grass diversity (or lack thereof). The seeds of a stiltgrass can remain active and viable in the soil for up to five years, even without an active, live plant aboveground (source). One plant can produce 100-1000 seeds, and they are spread by all methods: water flow, wildlife,and by foot and vehicular traffic. Deer grazing will pick out and eat the native plants, passing over the stiltgrass, which only serves to indirectly aid in its expansion. They can grow anywhere, from full, complete deep shade to full sun with little cover at all, contributing to a large part of the problem (source).
  4. Snakeskin liverwort, Conocephalum salebrosum, also known as the snakewort or great scented liverwort, is extremely small and flat against whatever rock or log it grows on. It’s more or less flat, but the air chambers within the plant give it its distinctive texture, something akin to the aforementioned snakeskin. It prefers moderate to medium shade with consistently wet conditions (including the occasional complete submersion into water). Surprisingly, there is little information on this liverwort’s floral-faunal interactions, likely due to its diminutive size, although the size of its spores (relatively large compared to the plant), it is possible that animals could play a role in dispersal, albeit a minor one. They’re not great to smell, although it is distinctive – due to the large amount of sulfur and nitrogen they absorb from the soil, they have a tendency to smell like rotten eggs or stale urine (how neat) (source).