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.