Visit to a nearby gneiss flat rock outcrop — 2020-04-30

In the past couple of weeks, I’ve had the pleasure to visit a local, multi-acre flat rock outcrop to sample the unusual plant associations it has to offer. This is not my first blog post about this location, but since it is close by and the right time of year to see the best plants it has to offer, I thought I’d feature it again.

The outcrop is composed of a granite-like rock called gneiss. According to Wikipedia, “Gneiss (/ˈnaɪs/) is a common and widely distributed type of metamorphic rock. Gneiss is formed by high temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Orthogneiss is gneiss derived from igneous rock (such as granite).”

In most places at this site, it is black and white or gray, but I have seen some pink areas, as well. It is not completely flat, but it is comprised of several rounded dome-like structures separated by small valleys filled with vegetation. On top of the outcrop are found many natural depressions which often filled with sand from the weathering of the outcrop. These depressions can range from just a foot (~.3 meters) to 10 feet (3 meters) or more. There are also shallow gullies present from eons of erosion.

In these shallow depressions are found several interesting plants, including Diamorpha smallii or Elf Orpine. Along the edges of the outcrop domes, at their intersection with the woods, many other interesting ephemeral species grow. The surface of the outcrop is covered in most places by two rock-loving species: Grimmia laevigata or Grimmia Dry Rock Moss and a Parmelia species, which is a crustose rock Lichen. The Grimmia Dry Rock Moss forms scattered, shallow mounds and is a deep green when wet, but is a dull gray-green when dry. The Lichen is a bright, greenish-gray and lies flat on the rock surface. Here are examples of each:

Grimmia Dry Rock Moss

Parmelia species of Lichen

The first time I visited the site this year, the Elf Orpine was just coming into bloom. Even so, the white flowers contrasting with the bright scarlet-red leaves and stem was a fantastic sight. These plants are quite small; about a couple of inches (~5 cm) or so in height, and the 4-petaled flowers are only about 1/8 inch (~3-4 mm) wide. The succulent leaves are oval to round in shape, like tiny red jellybeans! These plants form a dense mat on top of the rock outcrop, usually in the small, wet depressions. However, they can be found growing directly in the Grimmia Dry Rock Moss. I believe this makes the most striking color combinations of red and green, so it is this combination that I usually seek out. Here are some examples of this — some images showing how tiny the single plants can be and still produce flowers:

I think it’s pretty impressive to see the dense mats of these tiny flowers closeup. Here are a few shots to show what I’m talking about:

What can be more impressive is a wide angle shot of these mats of plants scattered in the outcrop depressions:

But let’s not leave out the other associated wildflowers. As I walk the margins of the outcrop, there are some shaded spots, one of which holds water for much of the season. Here, is found an Isoetes or Quillwort species. On first glance, it looks like grass growing in the pool, but this is a special plant which does not flower, but it produces spores in a sac at the intersection of the leaf and the stem. Again, from Wikipedia: “Isoetes, commonly known as the quillworts, is the only extant genus of plants in the family Isoetaceae, which is in the class of lycopods. There are currently 192 recognized species, with a cosmopolitan distribution but with the individual species often scarce to rare.” I suspect this is a species such as Isoetes piedmontana or Piedmont Quillwort, which is found in the Carolinas and Georgia, but it takes close examination of the spores to be able to accurately identify these Quillworts.

Around this pool, are found several colonies of Packera tomentosa or Wooly Ragwort. Note the tomentose or wooly surface of the underside of the leaf:

Again, all around the margins of the outcrop, were clumps of the purple-magenta Tradescantia hirsuiticaulis or Hairystem Spiderwort.

While wandering from outcrop dome to outcrop dome, I spotted a familiar plant called Phacelia maculata or Spotted Phacelia. Although not rare by any means, it’s the first time I’ve seen it at this site:

There was one other strange “plant” I spotted hanging from the branch of a Juniperus virginiana or Eastern Red Cedar. This rather gross, fleshy thing turns out to be Gymnosporangium juniperi-virginianae or Cedar-apple Rust, a fungus that affects both Eastern Red Cedars and domesticated Apple trees. According to www.FloraFinder.org, “Cedar apple rust lives out part of its life on two different species of trees (making it a heteroecious parasite). Each of the trees, eastern red cedar and apple trees, must be fairly close together. (Sometimes the fungus inhabits quince or hawthorn instead of apple trees.) This fungus transmutes itself through several stages of development. In the phase where it takes up residence in eastern red cedar, it produces uneven light brown sacs about an inch around. The sacs become rounder and resemble an oak gall. That is, until they begin pushing out orange columns, creating a structure that looks a little like a rusty World War II mine. The columns continue to exude, becoming a Medusa-like cluster of orange, slimy tentacles. The tentacles are actually “spore horns,” and they release spores that develop for a time and become airborne. Some of these land on apple trees, where they grow, coating the leaves with an orange-yellow blister-like “rust.” This in turn eventually releases more spores that infect new eastern red cedars, continuing the cycle.” This is a two-year cycle — one year spent on Apple trees, the next year on Eastern Red Cedar.

Here is an image of the “spore horn” stage of the fungus:

Teaser for next week: I could have spent many hours at this site as I have in the past, but I had one other place in mind to visit. Last year, while searching for a rare, undescribed Trillium, I spotted a number of the winter leaves of Aplectrum hyemale or Puttyroot orchid. Mid-May is a good time for these beauties to be in full bloom, but what with climate change affecting so many of our Spring wildflowers, I thought I’d better check on these plants before I missed their blooming. I arrived at the site, gathered my camera gear, and walked up the heavily eroded trail to where I had seen the plants last year. When I had earlier spotted the leaves, there was no understory of plants showing any leaves, so spotting the winter leaves of the Puttyroot orchid plants was easy. On this visit, however, the understory was fully leafed out, and I found myself standing in the midst of two equally obnoxious species: Urtica dioica or Stinging Nettle and Toxicodendron radicans or Poison Ivy. The forest floor was completely covered by these plants, and only by brushing them aside, was I able to find the withering leaves of the orchid plants.

However, persistence rules, and managed to spot a few early bloom stalks of the orchids. Most of the couple of dozen or so that I found were showing only buds, but I did find a couple of plants that were a bit farther along. Here is a sample:

Hopefully, there will be many more in full bloom next week.

Stay tuned…

–Jim