Ultramafic Bedrock

The hairstreaks and elfins in the genus Callophrys are some of my favorite butterflies. They are tiny, usually not much bigger than a dime. Their wings range in color from brilliant green to iridescent brown, blue and even pinkish. Elfins especially fly only early in the season, so I was anxious to try to see and photograph some before they disappeared for the year. A late April trip to Quarry Gardens at Schuyler provided the perfect opportunity. Extensive stands of short-leaf and Virginia pine with eastern juniper in the understory — the host plants of pine elfin and juniper hairstreak — grow there. Brown elfins have also been recorded, although their host plants, blueberries, are less numerous.

Golden Ragwort at Quarry Gardens

Quarry Gardens is a botanical garden designed to showcase the flora and fauna native to Schuyler, VA and the surrounding area. The Center for Urban Habitats inventoried the plants and animals naturally occurring there, and used that information to design and plant gardens representative of particular native plant communities. It lies partly on top of a formation of soapstone rock, and several abandoned, water-filled, soapstone quarries are on the property. It is home to fragments of a state rare plant community — ultramafic woodland — which only grows on magnesium rich (ultramafic) rocks like soapstone. Many locally and regionally uncommon species have been documented there. For more information about Quarry Gardens’ unique history, geology, plants and animals, see my older post: Quarry Gardens: Ecosystem Modeling Under Geological Constraints.

Bernice Thieblot and Devin Floyd — the owner of Quarry Gardens and the director of the Center for Urban Habitats, respectively — met my brother, Theo, and me at the gates. My friend Drew and a photographer named Emily soon arrived. We walked down to the visitor center, where a large patch of golden ragwort was in full bloom. We hoped to find elfins nectaring on the ragwort, as Devin had seen them there last year. Juvenal’s dusky-wings and native bees buzzed around. It wasn’t long before we spotted what would be the first of many juniper hairstreaks, drinking from a ragwort flower. We all pressed forward, hoping to get a picture of this stunningly green little butterfly.

Juniper Hairstreak (Callophrys gryneus) on golden ragwort (Packera aurea)

We decided to meander down the path that led around the old quarry pits. It was cool and shady under a thick canopy of pines. Lichens carpeted the ground in places. The mulch covered trail led down rock steps into an area planted with rich forest spring ephemerals. Mayapples, Solomon’s seals, wild geraniums, dwarf larkspur and wild ginger bloomed near the path.

We emerged from the trees into a small meadow, sloping down towards the edge of the water in the quarry pit to our right. The white flowers of pussytoes and wild strawberries were just beginning to open. Suddenly, Theo called out that he saw an elfin. Drew and I rushed over, and we watched it land on a barely opened pussytoes flower. One of its hindwings was damaged, but it was able to fly well enough to make getting a good photo difficult. Eventually it settled down, and we watched as the brown elfin tilted its wings into the sun. For a moment, the color seemed to change from plain brown to a rich assortment of pinkish and orangey hues.

Brown Elfin (Callophrys augustinus) on pussytoes (Antennaria sp.)

We left the brown elfin and continued down the trail. We looked for mountain bellwort, one of the rare plants growing at Quarry Gardens. We were excited to discover all 10 of the plants growing there in full bloom.

Mountain Bellwort (Uvularia puberula)

Drew, Theo and I walked to a swale planting, filled with golden ragwort, swamp rose, marsh marigold, skunk cabbage and various sedges. Emily, who had been wandering around separately from us, showed us a picture of a pine elfin she had just seen. Pine elfins look like brown elfins, but their wings are covered with intricate pink and brown mottling. They are also less common and more difficult to see than brown elfins. We fanned out, scanning the ground and the sky trying to re-find it. I decided to walk down by the edge of the quarry pits, where I found my first of year Selys’ sundragon, but no pine elfin.

Selys’ Sundragon (Helocordulia selysii)

Just as I was getting back toward the seep, I heard Theo yelling his head off about a pine elfin. I ran toward him, and arrived just as he lost the butterfly into the trees. We set about walking around once again, desperately trying to re-find it. I caught movement out of the corner of my eye. Turning, I saw a nickel sized butterfly bouncing away from me. We chased after it, and soon the pine elfin landed. The sunlight sparkled off of its metallic wings in a way that photos never seem to do justice to. The white bands and mottling flashed in the light. Then, before I could even reach for my camera, it was gone.

Pine Elfin (Callophrys niphon), Photo by Emily Luebke.

As I was walking back, still hoping for another pine elfin to photograph, I looked at a small brownish butterfly sitting on an American holly leaf. I assumed it would be another juniper hairstreak — they were one of the most common butterflies out — or a brown elfin. To my surprise, I saw a white band on the hindwing, meaning it was not a brown but a Henry’s elfin — a first Quarry Gardens record!

Brown Elfin (Callophrys henrici) on American Holly (Ilex opaca)

In retrospect, I probably should have realized it might have been a Henry’s sooner, as it was sitting on a holly leaf, which is a host plant for Henry’s elfin. With three species of elfins in one day, I was ready to forego my dreams of perfect pine elfin photos. Maybe next year…

The Quarry Gardens property was used as a soapstone quarry between the 1950s and 1970s. After the soapstone industry abandoned it, the community used it as a dump until Armand and Bernice Thieblot bought it in 1991. In 2014 the Thieblots embarked on a mission to create a publicly accessible native plant botanical garden, showcasing the unique local native plant communities of the quarry’s soapstone geology. The Thieblots hired The Center for Urban Habitats (CUH) to plan and plant the gardens.

CUH has a very unique approach to landscaping, ecosystem modeling, which involves replicating naturally occurring plant communities in garden settings. When CUH approaches an ecosystem modeling project, they observe factors such as geology, topography, elevation, drainage, existing plants, and lighting to help them infer from experience gained during prior surveys elsewhere what plant community is best suited to each exact location. Their specialty is figuring out the “ecosystem trajectory” of an area based on these existing site conditions. CUH studied the Quarry Garden project area for six months prior to planting, conducting an extensive biological survey to identify and map the distribution of existing plant communities.

Today, the 40 acre Quarry Gardens consists of nine main sections, each with numerous native plant gardens. Two huge, semi-rectangular water-filled pits, the remnants of the old quarries, dominate the center. If you look closely at the tall, vertical soapstone walls of these quarry pits, you can see the grooves in the soapstone left by the quarrying process. Piles of giant discarded soapstone chunks are distributed around the property. From the parking lot, the land slopes gently down towards the quarry pits. It continues to slope down on the other side of them, all the way to a small, meandering creek, which flows through a sunny, wet clearing just off the property. Two gravel roads lead around the quarry pits from the parking lot, one traveling the parameter of the property, and the other forming an inner loop around the quarry pits. From these roads, one can see most of the beautiful plant communities that have been planted here, from the bright flowers of the viewing platform prairie to the dull greens of the piedmont hardpan forest. The planted gardens blend perfectly with the surrounding natural plant communities.

Native landscape installation at the Viewing Platform, including niches for barrens,
hardpan swales, and prairie.

CUH learned about the geology of Quarry Gardens mainly from observing sections of exposed rock and the existing plants. They saw piles of soapstone boulders left over from the quarrying process, and the huge portions of rock that were revealed in the walls of the quarry pits. They also studied the present plant communities to infer the type and location of the underlying geology. They found that the plant communities could be divided into two main groups based on their tolerance of either ultramafic, a high mineral soil type with more magnesium than calcium, or acidic soil conditions. Ultramafic soil is so high in magnesium that it is toxic to many plants. CUH knew that soapstone bedrock, which includes many different types of ultramafic rocks and minerals, had to underlie plants that could tolerate ultramafic conditions. Similarly, CUH inferred that the Charlottesville Formation, which consists of mineral poor sedimentary rocks, must underlie the observed plants in the “heath” community, which occur in acidic, nutrient poor soils. Later in their process, CUH conducted soil tests, which provided more details about the geology.

View from the prairie below the viewing platform. Monarda, Solidago,
Eupatorium, and Pycnanthemum command this view.

The soapstone bedrock that underlies most of Quarry Gardens supports some very rare plant communities, including ultramafic woodland. Fragments of this nearly vanished plant community, dominated by old post and blackjack oaks over an understory of little bluestem, remain around the parking lot of Quarry Gardens. The most abundant tree in the ultramafic woodland at Quarry is Virginia pine, a species that under natural fire regimes would have been less prominent. Ultramafic woodland is so rare in Virginia because it can only be found on ultramafic rocks, like soapstone, and it requires periodic disturbance in the form of fire to keep less fire-adapted plants like the Virginia pine from encroaching. Since soapstone is such a rare and commercially desirable rock, quarries have almost completely destroyed ultramafic woodland in Virginia.

Two other plant communities that grow over the soapstone bedrock at Quarry are piedmont prairie and hardpan swale. Gardens showcasing these communities are prominently located in front of and behind a viewing platform that overlooks the large quarry pits. Under the thin soils of the prairie and hardpan swale lie huge soapstone boulders, remnants of a filled in quarry. The gaps between the boulders are filled with smaller bits of soapstone, such as pebbles and soapstone silt. Due to this, the drainage in the viewing platform area varies extremely widely. The piedmont prairie drains immediately and is hot and dry for most of the year, while the hardpan swale is virtually always wet.

The extreme drainage conditions and high magnesium levels of the prairie combine to make this area only inhabitable by the toughest species growing in piedmont prairies. CUH chose species that could survive the extremely dry and high magnesium present by selecting piedmont prairie species that have been found growing on serpentine barrens and ultramafic barrens, which share these harsh conditions in an even more dramatic fashion. Forbs chosen for their toughness and tolerance of magnesium include hoary mountain-mint, gray-goldenrod, tall thoroughwort, white colicroot, and glade wild quinine. Important grasses included poverty dropseed and little bluestem.

Invasive Species Assessment_Ultramafic Prairie.JPG

Center for Urban Habitats staff, Soizic and Rachel, inspect the prairie installation
during its first season. Non-native grass seedlings and forbs are plucked out and replaced by
dominant ultramafic prairie species like little bluestem.

Looking at the viewing platform prairie, one would never know how challenging a growing environment it is. Most of the plants have flourished here, creating a colorful testament to the resiliency of native ecosystems. Bold clumps of hyssop-leaved thoroughwort with feathery white plumes buzzing and humming with insects towered over smaller species. Gray goldenrod, showy goldenrod, sweet-scented goldenrod, and wrinkle-leaved goldenrod all bloomed profusely. Over to one side, near a quarry pit, the triangular leaves and strangely shaped flowers of spotted bee-balm accented the area.

Silvery checkerspot butterflies, along with 40 other species of butterfly have been noted at Quarry Gardens. Many of them enjoy the mountain-mints there, including narrow-leaved, hoary, and short-toothed mountain-mint.

Plants were selected for the hardpan swale that tolerate poor drainage, and that had been documented locally in magnesium rich hardpan swales. Winterberry, golden ragwort, and blue mistflower were prominent. The blue mistflower was especially noticeable in September, as it created brilliant cushions of blue flowers that seemed to float above the wetland sedges. Lush longhair and sallow sedge blanketed the ground.

Blue Mist flower is a guaranteed success in the harsh conditions presented by storm water
management swales. It does well in the magnesium saturated hardpan swales at Quarry Gardens.