This week for Flora and Fauna Friday we have another of our large and lavish lavender legumes, Atlantic Pigeonwings (Clitoria mariana).
Atlantic Pigeonwings is a species of legume found throughout the southeastern United States and all of South Carolina. It’s most abundant on dry, sandy soils and is thus found on barrier islands, high sand ridges on the Sea Islands, and Longleaf Pine savannas on the mainland. Being a legume, it has a leg up in these thin sandy soils through its ability to fix nitrogen. Legumes are able to trade sugars to the symbiotic bacteria living inside their roots, which in turn fix nitrogen from the air. Atlantic Pigeonwings is a perennial vine that grows a small tuberous rhizome underground and a thin, wiry stem above the earth. The vine climbs through twining but rarely reaches above ankle high, more often snaking across the soil as a groundcover. Its leaves are alternate and compound, composed of three simple leaflets. There’d not be much to show for this plant if it wasn’t for it showy flowers.
Atlantic Pigeonwings’ bloom time starts in June, peaks in July, and lasts through August. Its flowers are about an inch long and twice as wide. They have that classic pea-flower form of one large lower petal and two smaller upper petals, which form a hood over the anthers and stigma. The petals are all a pale-lavender in color, with the lower petal possessing a streak of white down the center that’s flanked by bowing brindled bands of a darker purple-mauve. Atlantic Pigeonwings’ flowers are specially shaped to guide Bumble Bees straight to their anthers, forcing them to take a dusting of pollen if they’d like a sip of nectar. However, many butterflies are able to cheat this system, using an elongated proboscis like a silly-straw to steal sips at a distance. One specific butterfly, the Long-tailed Skipper (Urbanus proteus), also hosts on Atlantic Pigeonwings, laying eggs on its leaves and its caterpillars then munching away at the foliage and flowers.
Atlantic Pigeonwings has a very similar looking cousin who also grows across the Southeast, Spurred Butterfly Pea (Centrosema virginianum). I’ve covered that species previously and it differs in a few key ways from today’s Pigeonwings. Spurred Butterfly Pea is more shade tolerant, grows in damper soils, has wider leaves, climbs higher, and has a flower that’s nearly circular and with no purple streaking on the lower petal.
This week for Flora and Fauna Friday it’s the hovering hunter lurking on every wetland’s edge, the Common Green Darner (Anax junius).
The Common Green Darner is an aptly named dragonfly. It’s common, abundant, and widespread. It’s found across all of South Carolina and the whole of the contiguous United States. The Common Green Darner is a big dragonfly, growing to about three inches long. Their thorax is solid Scheele’s-green with their head a more yellowish shade and sporting two huge compound eyes. For some color contrast, in males their abdomen is a brilliant turquoise-blue and, in females, a faded cinnabar-red. Their wings are mainly clear, with a faint wash of amber along the veins and a straw-yellow pterostigma near the tip. The family name “darner” comes from the shape of their abdomen and its cerci, the terminal appendages at the abdomen’s tip. In many Darners, the cerci of both sexes are long and, when at rest, overlap with an “eye of a needle” shape, giving the whole abdomen the silhouette of a darning needle, hence ‘Darners’. Cerci, along with the epiproct in males, are collectively called “claspers”. Males use their claspers to hold onto a female’s neck while mating. The Common Green Darner is unique among our southeastern Darners for laying eggs in tandem. Males continue to cling to the female after mating, even flying in line with her, until she lays her eggs. Eggs are often laid under floating vegetation or debris on the surface of a still pond or freshwater marsh.
The baby dragonflies hatch as nymphs, called naiads. The little naiads are just as voracious of predators as ‘ma and ‘pa, lurking in the murk to ambush unsuspecting prey with their projectile mouths. The naiads will patrol their watery nursery, sometimes for several years, until large enough to eclose into adults. Adult Common Green Darners, like all other dragonflies, are skilled hunters and agile acrobats. They nourish themselves on a steady diet of anything smaller than them that catches their omnidirectional eye in the sky. Darners, unlike most dragonflies, rarely land during the day. Common Green Darners prefer to hover on the wing or course across the water at speed in search of prey.
Common Green Darners are powerful flyers and will travel long distances to find a suitable abode, staking a claim collectively at every suitable pond and puddle in sight. They also perform a multi-generational migration, similar to the Monarch butterfly. Common Green Darners fly north each spring in search of open territory. They start a family there and then pass away. Late that summer or the following year, their offspring emerge and circle back south to escape the cold and hitch their wagon in the sub-tropics. Their grandchildren emerge in fall and repeat the multi-generational circuit the following spring. This allows the species to live a nomadic lifestyle and take advantage of a much wider geographic range, becoming more abundant, staying genetically diverse, but never over-specializing to one specific habitat or eco-region.
This week for Flora and Fauna Friday we have a wildflower that’s a feast for pollinators, Savanna Mountain-Mint (Pycnanthemum flexuosum).
Here in the South Carolina coastal plain, about seven species of Mountain-Mint can be found growing wild. Of those, Savanna Mountain-Mint is by far the most abundant here in the Lowcountry. Most all of our Mountain-Mints follow a similar physical pattern. Their growth is perennial, dying back to the roots in winter and spreading laterally underground all the while. They’re a large wildflower, growing waist to chest-high on oppositely arranged branching stems to create a small bush. Atop that bush will emerge small floral disks studded with white flowers and often perch above a ring of silver-washed leaves. Our subject today, Savanna Mountain-Mint, fits this generic mold well but with a few standout features to distinguish it from its relatives.
Savanna Mountain-Mint is on the smaller side for its genus, reaching up to about hip-high. Its leaves are thin and simple and shrouded in a faint silvery haze of fine hairs. Their stems share that same pale haze and they also bare the trademark square cross-section of the Mint Family, Lamiaceae. This species has a greater proclivity to spread through underground roots into a cluster than other Mountain-Mints, due to its preferred home in the fire prone Longleaf Pine savanna, a habitat where vegetation can be volatile but roots oft run deep. With the onset of summer, Savanna Mountain-Mint will begin to bloom, peaking in early July. The calyx of this species, the cup of leaves beneath each individual flower, produces five long, white points. This gives the flower clusters of Savanna Mountain-Mint an appearance like flattened pincushions. From this cluster emerges the actual flowers, about a quarter-inch wide and white with small magenta dots on their lower lip. Often times, only about a half-dozen flowers are present at a time on any lone cluster, with fresh flowers appearing every few days.
Like most mints, Mountain-Mint flowers are tubular in shape with a bilaterally symmetrical corolla of five petals. Two petals hang above the entrance to the tube and three fan out flat beneath it. This shape corrals pollinators, like a door with an awning and a porch, encouraging them to approach the flower from just one direction. This forces insects to contact an anther or stamen if they want a drink of sweet, sweet nectar, which in turn ups the odds that they’ll pollinate the flower. Savanna Mountain-Mint, and the genus in general, is an exceptional pollinator plant. They are enjoyed by pollinators of all shapes and sizes, from the minutest bee to the broadest of butterflies. Savanna Mountain-Mint is rather drought and heat tolerant for the genus and adapts well to many sandy soils, making it a good addition to native plant gardens here on the Sea Islands.
This week for Flora and Fauna Friday it’s the gray-green window hopper, the Squirrel Treefrog (Hyla squirella).
The Squirrel Treefrog is found throughout the coastal plain of the Southeast and the whole of the South Carolina Lowcountry. It’s the most generalist of our Treefrog species and can be found in most moist forest habitats and across the Sea Islands, even tolerating some brackish conditions. They’re on the smaller side for Treefrogs, at an inch-and-a-quarter long, and range in color from lime-green to mottled khaki-brown to a pale greenish-gray, and everything in between. Thus, they can be a real devil to identify, especially since Squirrel Treefrogs lack any distinctive features. You have to use process of elimination most of the time. If it lacks the white flank strip of the Green Treefrog (H. cinerea), the warty skin of the Cope’s Gray Treefrog (H. chrysoscelis), and the yellow thigh spots of the Pinewoods Treefrog (H. femoralis), then you can be decently sure it’s a Squirrel Treefrog!
Another way to identify them is through their song. The male Squirrel Treefrog’s song is a monotonous string of the phrase “bahk”, a gravelly croak repeated about twice a second. They get the “squirrel” in their common name from their song, which is reminiscent of the scolding calls of an Eastern Gray Squirrel (Sciurus carolinensis). Squirrel Treefrogs are known for their “rain calls”, singing immediately after the onset of rainy weather, wherever they happen to be hanging out. Like all our Treefrogs, they rely on ephemeral wetlands to breed. Places that flood for prolonged periods after heavy rain but dry out during the year, keeping the wetland free of fish and making a perfect nursery for tadpoles.
Squirrel Treefrogs are the most likely amphibian in the Lowcountry to set up shop around your home. About your place they’ll hide from the day’s rays behind shutters, between pots, and up downspouts, only piping up to celebrate a storm cloud. At dusk during the warm months they’ll emerge to chase insects, attracted to porch lights and the amber glow of windows.
This week for Flora and Fauna Friday we spy a native grass just beyond the surf and rising above the turf, Pinewoods Fingergrass (Eustachys petraea).
Pinewoods Fingergrass is native to the southern coast of the United States, from Texas through North Carolina. Here in South Carolina, it’s found in all our coastal counties and throughout our Sea Islands. It thrives on our young marine soils, coarsely sandy and rich in calcium from pulverized shells. I most often encounter it on Barrier Islands in healthy maritime forests, more inland on sandy ridges in the pineywoods, or along the shoulders of limestone roads in either.
Pinewoods Fingergrass is a perennial warm-season grass. It spreads weakly through running stolons into a loose clump but mainly disperses about the landscape through seeds. Its leaves are a soft blue-green and grow upward to about a foot in length. It begins to flower in mid-spring and continues through the end of summer. Its innocuous grass flowers chain together into one-sided comb-like spikes. Often their flower head is comprised of five spikes, lifted upward to two feet on a central stalk. This flower stalk arrangement resembles a hand reaching upwards to the sky and it provided the plant its “fingergrass” common name.
Pinewoods Fingergrass is a hardy native grass and can be a great addition to coastal yards. It does well in both full sun and partial shade. It’s well adapted to our coarse, sandy sea island soils with great drought tolerance and high resistance to saltwater intrusion and salt spray. As a grass, it’s mainly ignored by deer and likely a host plant for several species of our Grass Skipper butterflies. Unlike nonnative turf grasses, Pinewoods Fingergrass spreads sparsely and politely, allowing it to play nicely wildflowers in native plant gardens and alternative lawns, without taking them over.
This week for Flora and Fauna Friday we uncover a hidden gem, the sapphire pendant on the pineywoods, the Indigo Bunting (Passerina cyanea).
In the sweltering heat of the summer savanna, below a bluebird sky, a cascade of double notes catches the ear and draws the eye. A cerulean speck trumpets from a treetop, anointing a pine with a rare drop of blue spilled down from the sky. As you strain your eyes to resolve its form, the drop plummets further from the tree, curving on the wind before it collides with the Earth and sinks within the grassy sea of green that flows across the savanna. As quick as it fell it buoys back into sight. Set on a low bough of a flame charred shrub, a brilliance of blue shines like a sapphire amplified in the sun. A male Indigo Bunting presents in rare form.
The Indigo Bunting is found throughout the eastern United States from spring through fall, but under the summer sun is when they shine. They dwell on the boundary of forest and field, in open woodlands, clear cuts, and fringes of farms. Here in the Lowcountry, the Longleaf Pine savannas are their favorite haunts, a perfect middle ground between woodland and grassland. Indigo Buntings are most often heard before they are seen. Males fly to the tops of the tallest trees and serenade the savanna in bird song. Their song is a distinctive stuttered warble, with every phrase spoken twice before moving to the next. When they decide to drop down to the forest floor to forage, you may be blessed enough to watch one up close. Females are camouflaged, pale-khaki below, faded-chestnut upon the back, and ebony in their wings and tail. Contrastingly, male Indigo Buntings are dyed a deep indigo-blue across almost their entire body. The black between their eyes and their pewter-gray bill and down their flight feathers only serves to compliment the richness of their blue plumage. This blue changes in hue depending on how light hits the bird. This unstable hue is due to this being a structural color. Rather than a pigment dyeing the feathers blue, the microscopic shape of the feathers’ vanes force only blue light to reflect. Meaning the stronger and bluer the light, the bluer the Indigo Bunting glows.
This week for Flora and Fauna Friday it’s the saffron signal of the summer solstice, Golden Canna (Canna flaccida).
Golden Canna is a common plant down in Florida but scarcely scattered on the landscape here in the Lowcountry. It’s a rare sight most anywhere in South Carolina but we’re blessed with a wild patch or two on Edisto Island. It grows in saturated mucky soils in freshwater marshes and is tolerant of submersion during the growing season. Golden Canna is a large perennial wildflower that spreads below the soil through rhizomes. Its leaves are large at over a foot long, tongue-shaped with a pointed tip, yellow green in color, and held upright around its fleshy stem. The foliage grows to just above waist high.
Golden Canna begins to bloom in mid-May and continues through mid-June. Its flowers are hung above the foliage, a frilly folded funnel of pastel-yellow unmistakable as anything else. These flowers attract bees and large butterflies, particularly Swallowtails, to pollinate them. Pollinated flowers mature into seedpods about the size and shape of a starfruit but fuzzy and pale-green. These seedpods dry over time and their skin disintegrates, revealing magazines of hard, round, and black seeds the size and shape of 00 buckshot.
Golden Canna makes for a good wildflower addition to most pond banks and rain gardens. They do best on rich, saturated soils and with plenty of sun. However, they’re frost intolerant. So the subtropical Sea Islands are where they’ll thrive most reliably. They attract pollinators when in bloom, have handsome foliage when not, and that foliage is the larval food for the Brazilian Skipper butterfly (Calpodes ethlius).
We have two non-native Cannas floating around Edisto Island as well, Indian Shot (Canna indica) and Garden Canna (Canna X generalis). Indian Shot has red flowers with narrow petals and broader leaves held more perpendicular to the stem. Garden Canna is a catchall taxa of hybrid plants and thus comes in a hundred different forms. However, it most often has darker, larger foliage. Both can readily be separated from Golden Canna by their seedpods, which are half the size, roughly spherical, and held upright.
This week for Flora and Fauna Friday we have the aerial ace roosting in your rafter space, the Barn Swallow (Hirundo rustica).
The Barn Swallow is a cosmopolitan bird species, being found across the temperate regions of the world. They join us here in the southeast for our spring but head down to the southern hemisphere as the days get shorter. They live their lives riding the wake of spring, in a loop of infinite summer they daydream of Icarus, circuiting half the globe to chase the sun.
The Barn Swallow is an unmistakable bird, by both color and shape. Their back is a deep and shimmering iridescent indigo. A barely detectable black mask surrounds their eyes, contrasted by a forehead and throat of rich rust-red that stains downward to their ruddy breast and belly. Their bill is small and their legs smaller, both ill-equipped for a life foraging along the ground. Barn Swallows have higher ambitions, skyward eyes. Their wings are long and pointed and their tail long and forked, the eponymous “swallowtail” shape. These long and pointed wings allow for high speed flight and that forked tail serves as a rudder for aerial agility. All this is needed, as Barn Swallows hunt on the wing.
Like all our swallows, Barn Swallows are “hawkers”, they catch flying insects for food. Swallows spend their days searching for listless insects flying upward on thermals. Screaming through the screaming Barn Swallows fly with unmatched precision as they hone in on prey. Then, mouth agape, they gulp down bugs, beetles, moths, dragonflies, and all manner of unlucky insects midair. They even drink on the wing, skimming the water’s surface to siphon a sip. They only land to rest and to nest.
Barn Swallows get their common name from their preferred nesting habitat, barns! Well, really any open air human structure with a roof will do. Much like their cousin the Purple Martin, Barn Swallows have discovered the marvel of human engineering and the convenience of free rent from squatting in someone else’s house. Barn Swallows prefer to nest under bridges and piers or in hay lofts and pole barns. Anywhere with a dry roof overhead, air flow underneath, and a path for quick entrances and exits will suffice. In nature, this would have been caves and cliffs. But here on Edisto, and in much of the Lowcountry, we don’t have any rocks nor elevation to speak of. So the floor joists under elevated houses have become an enticing nursery for any Barn Swallow couple out house hunting. The closer that structure is to fields, ponds, and creeks, then the more ready access Barn Swallows have to food and water and thus the more attractive the nest site. Barn Swallows build their nest like adobe, wet mud held together with dried grass, laid one beak-full at a time to form a cup stuck to the side of a wall or beam. Here they’ll lay their eggs and often raise a clutch of four or five chicks at a time. Like most squatters raising five kids, Barn Swallows tend to make a mess of the place and leave behind a great quantity of guano. But they do pay back a little for their inconvenience. Barn Swallows, just like Purple Martins, help with pest control, feasting on agricultural pests and blood sucking insects wherever they stake their claim.
This week for Flora and Fauna Friday we have the cradle of Carolina’s Monarchs, Aquatic Milkweed (Asclepias perennis).
Aquatic Milkweed is found throughout the Lowcountry, ranging from South Carolina west throughout the southeastern coastal plain and north up the Mississippi River valley. It’s a perennial wildflower that grows in bottomland forests, floodplains, and the mazes of ditchwork and backwaters that permeate and diffuse them. Moist, rich soils that flood seasonally are a must have for its natural niche. Aquatic Milkweed grows to knee height in small clumps of singular stems. These stems are stacked with opposing pairs of narrow, blade-like leaves from base to leading bud. Come late May and through the end of July our Milkweed blooms.
Two to three dozen individual, pure-white flowers emerge together into a ball atop the tip of the plant. Each flower bears that unmistakable Milkweed shape: an hourglass of petals, five facing up in a tight packed bundle around, anthers and ovary, and five swooping down below into a showy skirt to catch the eye of passerby pollinators. New balls of flowers are merged beside the old, refreshing the display throughout the season and expanding across the stand of stems. Aquatic Milkweed flowers are a bright white beacon, a lighthouse standing amidst and shining across a choppy sea of green, cutting through the suffocating umbral umbrella of a bottomland forest. But what does the beacon beckon? It brings in butterflies! Most importantly the Monarch butterfly (Danaus plexippus).
Monarchs rely on native Milkweed plants to serve as nursery and nourishment for their caterpillars. Milkweed plants contain toxic compounds that ward off most herbivores. Monarchs have taken advantage of this, making themselves immune to the poison while also packing it into their own bodies as caterpillars, to serve as a lifelong shield against birds, lizards, and other predators. Monarchs are on the decline throughout much of the Unites States right now. They are even a candidate for federal listing as a threatened species. Their decline is due to impacts on all fronts at all stages of their life cycle. Monarchs are migratory, a trait that makes them resilient to large seasonal changes across a large landscape but simultaneously vulnerable to chronic, widespread habitat degradation or loss of critical refuge habitats. The most chronic threat they are facing comes from the widespread loss of Milkweed on the landscape over the last fifty years. Monarch caterpillars can only eat Milkweed. Without it, they will perish.
Here in South Carolina, Aquatic Milkweed is the most important host plant for our Monarchs. Its populations in our remote blackwater swamps are stable and consistent. Thus, Aquatic Milkweed provides a dependable network of host plants that our Monarchs rely on every spring. In fact, it’s so dependable many of our Monarchs in South Carolina no longer migrate! Well they still do, just not very far. From beaches to bottomlands, that’s as far as they go. Our Lowcountry Monarchs winter in the thermally insulated maritime forests of our beachfront barrier islands and our sheltered Sea Islands. Come spring they sail a couple dozen miles upriver, settling in the swamps and bottomlands of our blackwater rivers. There they lay their eggs upon Aquatic Milkweed and pass the mantle to the next generation. This new crop of Monarchs then disperses throughout our state throughout the year and makes use of the great diversity of Milkweed species found across our landscape. Then their children, or grandchildren, complete the circuit and return to their shelter by the sea to weather another winter.
If you’d like to learn more about the Lowcountry’s resident Monarch population, you can check out the research paper behind this discovery here:
https://www.nature.com/articles/s41598-023-37225-7.pdf
This week for Flora and Fauna Friday we have a bejeweled beetle in a thatch hat, the Palmetto Tortoise Beetle (Hemisphaerota cyanea).
The Palmetto Tortoise Beetle is found throughout the Sea Islands of South Carolina and Georgia, ranging south throughout all of Florida and west along the immediate Gulf Coast to Texas. They spend their life entirely on our native palms, including Cabbage Palmetto (Sabal palmetto), Dwarf Palmetto (S. minor), and Saw Palmetto (Serenoa repens). Upon the palms they slide up and down the fronds making their meals by scraping out the softer flesh from between the stringy fibers of the leaf. The Palmetto Tortoise Beetle is a captivating critter that deploys two fascinating defensive strategies throughout its life.
Adult beetles are a quarter-inch in length, dome-shaped, dimpled like a golf ball, and gleaming with a deep metallic blue-green that borders on black in the shade. Tiny orange antennae are their only contrasting color. The adult’s primary defense from predators is turtling up and tanking hits. Their shell is thick and its dimples provide extra structural reinforcement. Its glass-like texture and well-fit joints permit no handholds for prying predators. Even further, they have an iron grip. Their feet are modified into flat brushes. These furry feet are so finely divided that they electrically adhere at the sub-atomic level to a palmetto frond. It’s the same way lizards, like anoles and geckos, can scale plate glass, just shrunk down onto an ironclad arthropod. This makes Palmetto Tortoise Beetles functionally immune to being plucked from a palm frond by a passing bird or blown away by hurricane force winds. But as a young’un they have a far more juvenile form of defense.
Larval Palmetto Tortoise Beetles protect themselves from would-be assailants the same we protect ourselves from the sun, with a big straw hat. Only difference is our Beetle makes its hat from poop. How lovely! The first thing a baby Palmetto Tortoise Beetle does when it crawls out of its egg mass of a crib is start chowing down on a palmetto frond. The second thing it does is number two. The larvae will excrete long strands of what’s basically paper, compressed pulp pulled from the palmetto. Each strand is then glued to its back when complete and stacked atop the next. These strands twirl around into a basket that fully shields the larvae. This is called a “fecal thatch” and it helps shield the larvae from the elements and predators. Unlike the adult beetle, the larvae lack atomic Velcro feet. Instead they have sharp hooks that dig under the fibers of the palm frond, anchoring them like a roller coaster to its rail. When harassed, the larva hunkers down and waits for the predator to pass, hoping it loses its appetite as it vainly attempts to penetrate the fecal thatch. The larva carries this thatch with it throughout its life, even as an immobile pupa, until it matures, puts its childish past behind it, and dons a suit of armor instead.
