Vernal Pond Adventures
The largest of our vernal ponds in early April.
Once again I’m sitting beside our mountaintop vernal pond and wondering if this will be the year the wood frogs will make it out of the pond before the water disappears. A wood frog’s life span is about seven years, and for six years the pond has dried up before the wood frogs’ have fully developed. Some years their eggs are left high and dry; other years their tadpoles are.
A vernal pond is a temporary, fish-free wetland that fills in late winter or early spring and dries out by early summer in a good year. This pond is only several yards across and several yards long, depending on rainfall, and, unlike the tiny, 6-foot-wide pond at the base of First Field, I can’t get close enough to watch the courtship and mating of the frogs. I can hear their quacking calls, though, and I enjoy watching a wide variety of wild creatures that visit it even when I’m sitting quietly beside it, my back against an oak tree.
I find it incredibly peaceful to watch the pond as it reflects the trees in its still water. But this early March day a skim of ice over it glitters in the sunlight. Its surface has a medley of half circles and triangles artistically rendered by the ice-maker overnight.
On the thirteenth of March, as I near the vernal pond, circles appear in the water. I wonder if they can be disappearing wood frogs. I study the still, dark water and spot one small mass that I look at through my binoculars. A golden eye returns my gaze. I move closer and see a male wood frog stretched out in the water. Next to him is a stick with two clumps of wood frog eggs clinging to it. This unusually bold wood frog dives into the water but quickly resurfaces. Since I am still standing there, he sinks back under the water.
The vernal pond has already contracted, and I hope that the dark clouds rushing across the Allegheny Front will drop some rain on us and fill up the pond. But it doesn’t happen. Nevertheless, two days later, I find two wood frog egg masses in different areas. The gelatinous, fist-sized blobs contain several hundred eggs with black embryos.
By the 22nd of March, I count four separate egg masses, but the vernal pond is still shrinking. If the rain comes soon enough, the eggs may survive. And come it does, raining hard from 1:00 a.m. until mid-morning on March 24, filling up the vernal pond again.
The vernal pond in mid-March.
It’s almost a month before I return to the pond. At the beginning of April, while hiking on Sapsucker Ridge with my sixteen-year-old granddaughter Eva, she steps on a branch and I trip over it, my left leg landing hard on a pointed rock. Nothing is broken or fractured the doctors tell me, but my leg and foot swell up and turn black and blue. I have, after all, injured my tibia, the bone just below my knee. After days of being veranda-bound and more days of slow, short walks, I finally make it back to a vernal pond seething with insect life, most notably water striders walking atop the water and looking for mosquitoes resting on the water just after they have emerged from their “wriggler” larval stage.
Various species of diving beetles also swim in the water on the hunt for invertebrate and vertebrate creatures, including the wood frog tadpoles. I have always marveled at how these insects find a vernal pond, especially this one, isolated on a mountaintop half a mile from the nearest stream and that one intermittent near its source. Apparently, they are able to fly to it from such water. But some species of diving beetles actually overwinter in the basin formed by a dried up vernal pond.
The wood frog eggs have long since disappeared from sight, colonized by the symbiotic algae Oophila amblystomatis, which turns them green. It’s been cold most of the month, delaying the hatching of the eggs. But near the pond I stop to admire the patch of spreading spring beauties, the only place they grow on our property. This is an open, mixed-oak forest close to our neighbor’s logging operation that took place several years ago. Not much has regenerated and the vernal pond is not as shaded as it used to be.
It’s now the fourth of May and torrid summer weather has returned. I practically stumble over a porcupine as I approach the vernal pond and send the creature scrambling up a large red oak tree. The vernal pond is a veritable tadpole soup—tadpoles by the dozens wherever I look, floating near the surface to warm themselves up now that the trees have leafed out and are shading the pond. They need the solar heat to develop quickly into frogs before the pond dries up. First they graze on the symbiotic algae still clinging to their gelatinous cradle, and then they feed on algae and leaf material on the pond’s bottom. They also may feed on each other, those that hatched first preying on the latecomers.
Three days of hard, cold rain follow, and once again the vernal pond is overflowing and seeping over into a series of wallow-sized pools. My pond-watching becomes an almost daily discipline as I sit and watch the tadpoles eating, swimming, and basking in patches of sunlight. In mid-May I hear clucking as a hen turkey circles behind me. Maybe she is hoping to catch some tadpoles for brunch.
Water striders
Often the tadpoles join in aggregations of ten on a submerged stick. Then there is a sudden flurry and they separate, but in a few seconds they gather together again, performing their own watery tadpole ballet. In addition to basking in the sun, perhaps they are finding refuge from predators in a crowd like flocks of birds do.
By the twentieth of May a few of the larger tadpoles are developing back legs. I sit close to the water and watch as the tadpoles continually surface to feed on the detritus floating on the water, then submerge, each tadpole swirling the water into a circle. I try counting the circles to figure out how many tadpoles still inhabit the pond, but the confusion of circles quickly confuses me. Instead, I settle back and enjoy the ambiance of the pond and surrounding woodland having long ago learned to tune out the occasional train whistle and the constant traffic noise on Interstate 99 at the base of the ridge.
A mourning dove sings without ceasing. Red-eyed vireos, eastern wood pewees and a scarlet tanager frequently add their songs to that of the doves. Water striders skate along the water. A common green darner dragonfly buzzes over the pond. Then an American crow flies in like a kamikaze fighter plane, veers when it sees me, and silently retreats.
There are more days of rain and again the pond overflows. The pond water is so dark that I can’t glimpse the tadpoles, but dozens of circles that gradually subside as I sit in front of the pond indicate their presence. Sitting beside the pond, a sudden nearby gunshot startles the tadpoles as much as it startles me. Not only do they have sharp eyes but sharp ears too.
Near the end of May, I’m serenaded by a robin and scolded by a hairy woodpecker while I sit beside the pond. I also see a dark-eyed junco, which should have been breeding farther north on the Allegheny Front or beyond by now. A mourning dove flies in to catch insects from the pond and goes off in a flurry when it realizes I am there. A black-and-white warbler sings. Chipmunks scold. Mosquitoes that probably have hatched in the pond circle me and force me to move on after I catch a glimpse of a few more tadpoles with back legs.
My vigil continues in June. By then, I wonder if those tadpoles will ever change into bandit-masked wood frogs. On June 8 many heads pop up from the water and stay up even though most tadpoles still have tails. Two male robins hold a song fest while a female chases all comers to the pond as her spotted youngster bathes. Later a tufted titmouse takes a bath. Chipmunks chase around the pond and one scampers up to me, pauses at my feet to look, and then continue its race with its rival. A pileated woodpecker pounds on a nearby tree trunk.
Wood frog in mating season (in the tiny, spring-fed pool at the bottom of First Field)
All the while a pleasant breeze blows, keeping biting insects away. The pond is slowly shrinking, but it is still a bathing and watering hole for birds and mammals alike.
The following day I spend another session at the vernal pond serenaded by the same two robins. Little mouths surface to catch detritus spread atop the pond, and once I see a tiny froglet hopping over a small section almost as if it could walk on water. Froglets are supposed to be between a half and 7/8th of an inch when they metamorphose. Their watery life is ending and none too soon.
A chipmunk approaches me with much trepidation, and when I don’t move, it goes to the pond and drinks. Then it scampers off.
Suddenly, the robins begin high octane scolding as if, after half an hour, they finally notice me. On and on they scold, but at last they subside.
When I am too stiff to sit any longer, I get up and walk back to the field path. There I find an enormous pile of fresh bear scat that wasn’t there before. It looks as if the robins were scolding a bear.
A couple days later, as I’m sitting by the pond, I hear crashing in the woods that sounds like a bear. Sure enough, one approaches the pond, and I ponder my position. It’s obviously hoping for a drink and doesn’t see or scent me. At last I stand up, and the bear looks up, sees me, and flees.
The vernal pond continues to fill every time it rains, and slowly the froglets depart, although I don’t see them. But there are fewer circles in the water, less little heads surfacing, every time I visit. How wonderful that after so many springs when the pond dried up too soon, our aging population of wood frogs will finally get some newcomers. The young frogs will spread out, traveling up to several hundred meters in all directions, making new homes in the leaf litter, and preying on a variety of arthropods.
But even as the pond shrinks and the froglets leave, I still seek quiet time beside it. One day, late in June, I encounter an eastern box turtle, floating in a couple inches of water, its eyes closed. At first I think it is dead, but when I touch it, it opens its eyes. Later, I learn that eastern box turtles like to soak and feed in vernal ponds.
Wood frog found under a rock in Plummer’s Hollow Run in September
On another day, two doe wander past me and water at the pond while I sit a few feet away. Then they continue on their way. They never do detect my presence.
I can only wonder how many other wild lives are impacted by this small pond. Even though knowledgeable foresters will steer logging operations away from such places, most loggers either don’t know or don’t care about such refuges. Or they begin their logging operations in the fall when the ponds are dried up and they don’t recognize them for what they are.
My own life has been enriched by our vernal pond this water-full spring. Even after it is completely dried up, in broiling hot, droughty July, I wander back to sit under the oak shade. Where have all the wood frogs gone?
One day, on my daily walk, an adult wood frog hops across my path.
“There you are,” I say out loud as it hops quickly out of sight.
Grasses Wear Robes
learning a new grass
We never get very far when we go on a Pennsylvania Native Plant Society field trip. But we always learn and see more than we bargained for. Take the grass field trip to Rothrock State Forest in central Pennsylvania that my son Dave and I joined last July. Let by Sarah Miller of the Penn State Cooperative Wetlands Center, who is an expert on wetland plants and ecology, fourteen people from as far away as Lewisburg rendezvoused with her along Pine Swamp Road deep in the heart of the forest. When Miller handed us the draft of a key she had devised entitled “Do I Have a Grass, Sedge or Rush,” we realized that we would be identifying not only the grasses but also the sedges and rushes along the trail.
A quick glance at the intricately-designed five sheets of paper, and I knew that my dependence on the old jingle, “Sedges have edges and rushes are round and grasses are hollow and move all around,” would not suffice. In truth, I always forget what grasses are in that jingle so later I googled it on the Internet. Apparently, I’m not the only one who can’t remember the exact wording of the grasses part because I found several versions of it including “grasses have nodes from the top to the ground,” “grasses are hollow right up from the ground,” and “grasses wear robes all the way to the ground.”
Despite the multiple versions of the grass line in the jingle, it turns out that they are the easiest to sort out. If the stems are round, hollow, and jointed, with its leaves 2-ranked or 2-dimensional when viewed from above, it is a member of Poaceae — the Grass family.
three-way sedge
Sedges and rushes, on the other hand, are not as simple as the jingle implies and, in fact, took up the remainder of Miller’s key. For instance, the three-way sedge – Dulichium arundinaceum – which is common in bogs, swamps, marshes, lake margins and ditches, shares all the same characteristics as a grass except that its leaves are 3-ranked or 3-dimensional.
Still, there were several botanical terms I had to absorb as Miller launched into her identification of a couple grasses growing beside the road. “Node,” it turns out, is another word for the joints on a grass stem, which is called a “culm.” Those 2-ranked, alternate, parallel-veined leaves of grasses have two parts, the “sheath,” which surrounds the culm, and the “blade” which sticks out from the culm. Where the blade joins the sheath at the culm, on the inside usually is a papery structure or ring of hairs called a “ligule.”
I should have identified the first grass Miller showed us, but I was so intent on grasping the botanical terms that I didn’t even recognize the notorious Japanese stiltgrass until Miller named it. Also known as “Nepalese browntop,” “Mary’s grass,” “Nepal grass,” and “Japanese grass,” Japanese stiltgrass, Microstegium vimineum, was accidentally introduced into the United States in Tennessee, probably because the dried grass was used as packing material for porcelain. Since then, this invasive has spread to eastern states from New York to Florida.
Japanese stiltgrass in late September, Plummer's Hollow
Japanese stiltgrass thrives in disturbed areas. In the last several years, it has invaded the poorly-logged portion of our property that we purchased after it was cut 18 years ago. It spreads both by rooting at its nodes and by its seeds. Each plant produces between 100 and 1000 seeds that remain viable in the soil for at least three years. A native of not only Japan, but also Korea, China, Malaysia, and India, it seems to thrive in eastern North America almost everywhere from forests to fields, wetlands to roadside ditches, gas and powerline corridors to lawns and gardens.
Japanese stiltgrass doesn’t flower until late summer or early fall, but it was easy enough to identify the silvery stripe of reflective hairs down the middle of the upper surface of its alternately-arranged, asymmetrical, lance-shaped leaves.
To identify the next grass, the terminology was even more complex for my aging brain to grasp, and I never did sort it out until much later when I sat down with Agnes Chase’s excellent First Book of Grasses. First published in 1922, the Smithsonian Institution printed a third edition in 1959 in honor of Chase’s ninetieth birthday. My own 1977 hardcover copy was the second reprint of that edition. Despite nearly 60 years engaged in productive scientific work that resulted in more than 70 scientific papers, she is best know for this little gem of a book.
Chase was a self-taught botanist, but she became the dean of agrostology (grasses) after many years at the United States Department of Agriculture working for Albert Spear Hitchcock. She helped him compile the Manual of the Grasses of the United States, which she illustrated lavishly with her drawings, and then she revised all 1040 pages of the book after his death.
She also made two exploring trips to Brazil and another to Venezuela in the 1920s and 30s when she was in her fifties and sixties. Botanical collector Ynes Mexia, who spent a couple days collecting with her in Brazil, described her as “almost a human grass, who lives, sleeps, dreams nothing but grasses…”
Chase’s clear drawings and explanatory material finally made sense of Miller’s insistence that we must look carefully at a grass flower in order to identify it. A grass spikelet is the equivalent of a leafy flowering branch and consists of the flowers themselves or “florets,” which are held in the axils of small green bracts called “lemmas.” They, in turn, are enclosed in a second bract — the “palea.” The equivalent of a stem is called a “rachilla.” Below the grass flowers are two bracts without flowers — the “glumes.” All of these terms are important because often a grass can only be identified by its spikelets and their arrangements, for example, the shape of the glumes and the lemmas.
As we worked our way through the next grass, examining the spikelets in detail, Miller eventually identified it as Poa trivialis or rough bluegrass, a native of Europe but often cultivated here and found in wet meadows, swamps, and wet forests.
Rattlesnake Manna Grass, by Petroglyph on Flickr (CC BY-NC license)
Another spikelet she showed us was that of poverty grass, Danthonia spicata, in which a long hair emerged from between a pair of stiff hairs or teeth at the tip of each floret. And we admired the wavy branches of rattlesnake mannagrass, Glyceria canadensis — an easy way to identify this distinctive wetland grass.
We shuffled onward as folks stopped to look at every grass, sedge, and rush. Rushes (Family Juncaceae), Miller told us, have miniature flowers with three petals and three sepals, an arrangement called “tepals” that enclose a capsule containing three or more seeds. As an example, she showed us soft rush, Juncus effusus. This perennial native has densely-clustered stems and clumps of flowers that grow from the side of the stem.
Because the flowers of the soft rush “are individual, they are prophyllate, if they are in heads, they are eprophyllate,” according to Miller’s key, and that’s where the botanical terminology defeated me. I knew I would need many more hours to sort out and memorize words I had always avoided.
I had never had a botany course and tended to rely on pictorial field guides to identify wildflowers as well as the more common grasses, sedges, and rushes with the help of Ernest Knobel’s Field Guide to the Grasses, Sedges and Rushes of the United States and Lauren Brown’s Grasses, which also includes sedges and rushes. For an amateur like me these guides are invaluable. Still, they do take some work and occasional glances at botanical glossaries.
The rest of the plants we looked at were sedges (Family Cyperaceae), which usually have triangular solid stems, small flowers, and 1-seeded fruits or nutlets that are often called “achenes.” There are 15 genera of sedges in Pennsylvania, 160 species of which are in the genus Carex. This is, by far, the largest genus of flowering plants in the state. A couple that we saw with Miller was Carex folliculata and Carex torta, both common, native, wetland perennials and both known commonly as “sedge.”
We also looked at Scirpus cyperinus, another sedge with the common name “wool-grass,” which should explain why botanists prefer to use the scientific names. Other members of the Scirpus genus also have variations on the name “bulrush,” even though they are neither grasses nor rushes.
Botanizing at the Beaver Dam in Rothrock State Forest
After more than an hour, we reached the Beaver Dam as the wetland is known by the locals. Miller called our attention to another grass, Calamagrostis canadensis or Canada bluejoint, a denizen of bogs and swamps, as some of us deftly moved from sphagnum hummock to sphagnum hummock over the former impoundment and tried to avoid the places where knee-deep water flowed swiftly.
But one elderly man, in an attempt to catch a praying mantis, fell into the water.
“Bob’s down,” son Dave said. “Are you okay?”
As if in answer, he scrambled to his feet and showed us the mantis he held between forefinger and thumb. This was, after all, a group of amateur naturalists interested in every aspect of the natural world.
Next, a younger woman plunged in up to her knees and emerged muddy but cheerful. After that, we were even more careful.
Then Miller showed us another grass.
“It’s a Panicum,” she said.
“What is the species?” I asked.
“I have no idea. I have trouble with Panicum,” she answered. With that honest reply from an expert, I felt better about procrastinating trying to learn all the grasses, sedges, and rushes even on our mostly dry, mountaintop property. The least I could do, I resolved, was identify those plants.
ebony jewelwing damselfly at the Beaver Dam
The Beaver Dam wetland is a lovely place. Masses of purple steeplebush bloomed in the middle of it, and we knelt in the mud to examine the delicate flowers of blooming sundews with our hand lens. Ebony jewelwing damselflies flitted over the water, a wide expanse of cotton grass grew on the far side of the wetland, and large white pines towered over its edges.
But I was distressed to see the telltale tire marks of an all-terrain vehicle imprinted in the mud. It had been driven heedlessly through the sedges and rushes. Such incursions, especially in wetlands and along streambeds, continue to destroy habitat and frustrate those of us who value such places.
At last, we were marshaled back to our cars, and off we went. But the adventure was not over. The lead car suddenly braked to avoid a tiny porcupette crossing the road. Everyone stopped their cars and rushed to get a better look at it as it scurried into the underbrush. Son Dave scared it up a tree, which it looked as if it was climbing for the first time. At the first branch, barely six feet from the ground, it paused to rest, and eager naturalists and photographers gathered around to admire and take its picture. Only Dave had ever seen one before and that was on our property several years ago.
Then, farther along, at the side of the road, Dave spotted a wood lily (Lilium philadelphicum) in bloom. By that time, our car was on its own. All four of us got out to photograph that gorgeous, deep orange, purple-spotted wildflower standing erect on a stem above whorled leaves. This last, unexpected floral gift from Rothrock State Forest ended our grass field trip on a high note.
Lilium philadelphicum
All photos were taken by Dave on the day of the outing, except where noted otherwise.
Marcia with golden eagle (photo by Todd Katzner)
Marcia Bonta is the author of nine books and over 300 magazine articles. The blog portion of this website includes her popular “Naturalist’s Eye” column from Pennsylvania Game News, reprinted here on the 1st of each month. Unlike typical blog entries, these columns are written months in advance, usually about things that happened during the previous year. Read more…
