Tag Archives: fern

The survivors: the long consolation of ferns

Ferns along Hoo-Koo-E-Koo Trail, Larkspur, California by Betsey CrawfordSince the middle of March, when California’s shelter in place started, an acupuncturist friend has been offering weekly meditations via phone. At the beginning of each she asks us to imagine ourselves in a nurturing place in nature. Whenever I receive such an invitation, I invariably find myself sitting on a forest floor, trees reaching high above me, leafy branches arching overhead, sunlight glinting through the openings between the leaves. That is peaceful enough, but the most important element is that I’m surrounded by ferns, their graceful fronds gently touching my shoulders. I’m in a soft sea of wavy green. 

Why ferns? I could as easily imagine being in a meadow full of wildflowers. But there is something about ferns that speaks of peace and the deep quiet breathing of the green earth. I don’t remember a time I didn’t love them, yet I don’t remember them from my suburban childhood. But they were likely a part of the woods I lived in for several very young years. For they are happiest in the woods, growing enormous in the moisture-laden forests of the Pacific coast or in tropical rainforests, where they grow in the trees as well as at their feet. But some fern species also survive long dry seasons — a few are drought-tolerant enough to live in deserts — allowing them to have a foothold everywhere except the poles. For all their graceful delicacy, they are a very hardy bunch.

fern-and-hounds-tongue-along-Hoo-Koo-E-Koo-Trail-Larkspur-California-by-Betsey-CrawfordAs we would be, too, if we had survived for 360 million years, outlasting two major extinctions, feeding dinosaurs along the way. For 200 million years they were mostly enormous trees. Those are still with us, somewhat unfortunately. They are now the coal and oil that powers the industrial world. The ferns that we live among today — which include some tropical tree forms —  evolved around 160 million years ago, at the time the first flowers began to appear. Flower forms have proliferated over the eons. Petals, colors, leaf forms, stem length, fruits all continue to evolve because their habit of cross-pollination allows for a continuing creative mix of genes from different parents. This gives us the enormous variety of flowering plants covering the earth. 

The underside of a fern dotted heavily with spores. Photo by Betsey CrawfordFerns, on the other hand, evolved a different method. They produce spores, usually along the undersides of their fronds, stored in sori. When the spores ripen, the sori open and the microscopic spores  puff off in the wind. Once on the ground, they form a tiny new plant, a prothallus, which produces both egg and sperm. Whatever water is available allows the sperm to swim to the egg and fertilize it. The new fern is launched, with genes from one only parent. This process has still produced a variety of ferns, but minimally compared to flowering plants. We’ve named 300,000 of the latter, to just 12,000 identified ferns. Only a handful of those — 380 species — live in North America.

Ferns also frequently reproduce by rhizomes, fibrous stems that also hold roots, traveling just under the ground. Fronds pop up along their length. That’s how the forest floors in my neighborhood have become covered by them. I am blessed to have a place filled with ferns — pictured below — that I can get to any time I want. It’s not quite my meditative dream, where I almost disappear into fern fronds, but it’s a good substitute. 

Bench among ferns on King Mountain in Larkspur, California by Betsey CrawfordIt’s along a popular trail, so I’m unlikely to be there for long without my closest genetic kin passing me by. But when they have passed, I’m still among my cousins. We are in the midst of a worldwide call for recognizing our kinship with people who share everything but the most superficial differences. Less than 1% of human DNA accounts for the marvelous variety of people we see on a busy street any day of the week. Given our millennias-long struggle to recognize that we are infinite varieties of the same creative force, that every human is family, it can be a reach too far for some to realize that we are also intimately related to the green world around us.

And yet that is one of the consoling things about sitting among the ferns. They, too, are family. We share DNA, about 25% of it. Our respiration depends on the same cytochrome-c. Our circadian rhythms depend on the same PRMT5 gene. These reach back to our earliest forebears, the one-celled organisms that came to life in the thermal vents of the ancient ocean 3.8 billion years ago. Though our genetic ways split 1.5 billion years ago, their chloroplasts and my mitochondria continued to travel the same journey, powering us both with energy. The minerals in the rocks and dirt I sit on among the ferns are the same minerals structuring both our stems and bones and flowing in and out of our cells. All gifts of the earliest stars.

Ferns and fairy bells in the Hoh Rain Forest, Olympic Peninsula, Washington by Betsey Crawford

Ferns and friends (and lots of pine pollen) in the Hoh Rain Forest, Olympic Peninsula, Washington

And here is the most magical thing: they see me. They know I’m there. Indigenous peoples have always known this. Now plant scientists like Stefano Mancuso are exploring features common to ocelli, the simple eyes of insects and other invertebrates. They are also found in epidermal cells of both leaves and roots. Mancuso is building on insights from the early twentieth century, when Austrian botanist Gottlieb Haberlandt proposed that plants can register images. Another botanist, Harold Wager, took recognizable pictures of the English countryside using a variety of these epidermal cells as lenses. His achievement earned him a front-page headline in the New York Times on September 8. 1908.

Harold Wager's NYTimes headline about his finding that plants have visual abilitiesWhy was this insight forgotten for more than 100 years? Mancuso suggests the idea of visual ability in plants was simply too eccentric for anyone to follow up on it. This fascinates me. Those were the years when Einstein was revolutionizing physics, opening the entire universe. The nineteenth century saw an endless parade of fossil hunters, set off by the insights of Scottish geologist James Hutton, who wrenched earth’s history out of the bible. As did The Origin of the Species, published just a few decades before Haberlandt. Darwin’s son, Francis, was a champion of his work. It wasn’t that people weren’t used to new and challenging world views. What made the idea that plants have visual capability a bridge too far?

Botanist Harold Wager's photos taken using plant cells as lenses

Botanist Harold Wager’s photographs, taken using plant cells as lenses. Note the recognizable human head in the upper left.

Institutionally, things haven’t changed much. But there are now revolutionary plant scientists like Mancuso, Monica Gagliano, and Suzanne Simard who are paving the way with studies of plant communication, memory, choice, and decision making. Their work tells me that as I sit on the ground among the ferns they not only see me but feel me. Roots, which could be considered the brains of plants, are exquisitely sensitive. They would sense changes in the weight, the air, the light above them. Even sitting on the bench in my fern alcove above I would change the light and air, give greater weight to the ground, subtly alter the temperature. Plants respond to light and chemical signals in the world around them. What do they detect from the chemicals I give off? Do they read my mood? Do they know I’ve come for comfort and peace? Do they embrace me?

That’s how it feels to be among them. Their aliveness and our infinite interconnectedness is something I feel so deeply. I know their resilience, their strength, their persistence. I am among beings that have lived through long, long eons, some quiet, others ferocious. They have survived what most others couldn’t. They have grown everywhere. Nothing surprises them. They blow in the wind and upright themselves. They burn and start growing again. Floods wash over them, recede, they adapt. Forty-four million years of global cooling? They cope. The air grows dry and they figure out how to work with it. The air grows moist and warm and they’re even happier. Great ice sheets come and they wait 50,000 years for the ice to melt and then start growing again.

Unfolding fern frond in the Hoh Rain Forest, Olympic Peninsula, Washington. Photo by Betsey CrawfordThe visual softness of their graceful arches is deceptive. The fern spines are strong, hard to the touch, hairy. The fiddleheads are firm, almost fiercely held as they start to open. The leafy pinnae growing from the stalks are pointed, papery, even leathery as the fronds age. And yet they are — as a whole, a community — soft. Artemis, the goddess of the woods, passes easily among them, rustling them slightly. They move aside, bending and recovering, ever retaking their space in the cosmos.

Their existence gives mine more room to be, more depth to depend on. What sustains you? I was asked recently, and I immediately thought of the green world that means so much to me, and the earth it springs from. All my relations, as the Lakota say. A constant showering of nourishment and abundance. And when I know that I am part of it, that the same energy that flows through all flows through me, that’s where my energy comes from, my sustenance. When I lose that connection I’m scattered, anxious, feeling engulfed by life’s details. But I take heart from the desert fern that dries up and reconstitutes itself once the rain comes. It reminds me that the peace ferns provide is something I can carry everywhere, revivifying it as it wilts again and again in the jangling flux of human life.

Fern fiddlehead along Hoo-Koo-E-Koo Trail, Larkspur, California by Betsey Crawford

 

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Living light: the crucial miracle of photosynthesis

Maple leaves and ferns in the forest on Peterson Bay, Homer, AlaskaTo love plants is to be in awe of photosynthesis. Even when you know how it works, it’s still a miracle. And a crucial, we-wouldn’t-be-here-without-it miracle. Its ramifications are so vast that once it showed up, it dictated all of the evolution that followed.

It’s also complicated. There is, for example, a catalyzing enzyme involved called ribulose 1,5-bisphosphate carboxylase oxygenase, with a personality as confounding as its name. Mercifully, we don’t need to go fully into those weeds. For most of us, it’s magic enough to know that somehow sunlight turns into sugar. But it’s so fascinating that I’d like to invite you to take a walk with me through this lovely, cool forest, and on out into the history of life on earth.

Photosynthesis happening in a forest in the Wynn Nature Center in Homer, Alaska by Betsey Crawford

We’re walking in a sea of green because pigment molecules called chloroplasts in the tree leaves and fern fronds absorb all color wavelengths except the green ones. Those are reflected off the plants, and the highly sensitive cones in our eyes pick up the wavelengths and relay the information to our brains. So we see soothing, cooling green, a color widely associated with the serenity surrounding us in this quiet woodland.

Yet, every leaf and frond around us is pulsing with activity. Photons from sunlight hit the chloroplasts and their energy gets moved from one pigment molecule to another until it reaches special molecules in interior cells. There the energy excites electrons, which makes them pop into orbitals farther from their nuclei. Full of verve, these animated electrons start a cascade through surrounding, helper molecules, creating energy that pulls hydrogen ions into the center of the cell. 

Intense green leaves of red monkey flower (Erythranthe lewisii) and false hellebore (Verastrum viride) mean more photosynthesis. Photo by Betsey Crawford

Red monkey flower (Erythranthe lewisii) and a huge leaf of false hellebore (Verastrum viride). Most of the photos accompanying this post are from the north, where leaves are large and intensely green to capture all the light they can during short summers.

Missing electrons need to be replaced, and this first part of the process replaces them by splitting water molecules and grabbing electrons from the hydrogen atoms, whose remaining ions join the gang in the center of the cell. The oxygen disperses through the stomata, holes in the leaves that open and close as needed. This is the oxygen we breathe. The carbon dioxide we have been exhaling then floats into the stomata to be used in the next part of the cycle.

As the hydrogen ions in the cell’s center get more concentrated, they immediately want back out, pushing their way through an enzyme that creates ATP, the same energy storage molecule that our mitochondria create for us, by a similar electron process.

A wild flower meadow on Hudson Bay Mountain in Smithers, British Columbia., showing the wide variety of leaves for photosynthesis even in one small area.. Photo by Betsey Crawford

A wild flower meadow on Hudson Bay Mountain in Smithers, British Columbia., showing the wide variety of photosynthesizing leaves even in one small area.

Having run through their energy, these electrons enter a new cycle where they are re-energized by more photons to create NADPH. Thus the electromagnetic light energy from the fusion reaction in a star 93 million miles away becomes chemical energy in microscopic cells brushing our shins as we walk, along the way providing the oxygen we need for life. 

The chemical energy — NADHP and ATP — is then used by another process to take a gas — carbon dioxide — from the air and convert it to a solid state in the form of carbohydrates, which are strings of carbon molecules of varying complexity. (This is where the catalyst with the endless name comes in.) Thus carbon dioxide turns into food, as well as being ‘fixed’: removed from the atmosphere and stored in plants. This is why preserving and replanting forests are crucial to reversing global warming.

Prairie grasses in the Pawnee National Grassland, Colorado

Prairie grasses in the Pawnee National Grasslands, Colorado

There are variations in the whole process, even in the woods. The leaves at the top of the trees, in the full glare of the sun, are likely to be smaller and thicker than the understory leaves. That way they protect themselves from the full force of the sun’s energy. The lower leaves tend to be larger, thinner and more horizontal, and the ferns grow many wide fronds, allowing them to catch all the photons they can from the sunlight filtering through the treetops. Because it tends to be cool and moist in the woods, photosynthesis carries on with little hitch.

Once we walk out of the woods into a meadow of grasses, there are challenges that require further variation. In the cool, damp spring, grasses are in heaven, soaking up water and sunlight, feeding their blades and roots, developing seeds. Once summer brings its hot, dry weather, many grasses go dormant until fall or even the next spring. The ones that don’t, like the sturdy crabgrass in your lawn, have adopted photosynthetic habits that allow them to keep going in heat and aridity.

Engelmann's prickly pear cactus (Opuntia engelmannii) in Saguaro National Park, Tucson, Arizona by Betsey Crawford

The pads of cacti are modified stems which do the photosynthesizing. The spines are modified leaves, holding air around the flesh to protect it from the sun. This is an Engelmann’s prickly pear cactus (Opuntia engelmannii) in Saguaro National Park, Tucson, Arizona.

If we walk further on, into the desert, the problems of heat and dryness become acute. Desert plants, like cacti and agave, want to keep their stomata closed during the day to preserve water. Instead, they open them as the evening cools, and have evolved a way to take in and store carbon dioxide in the form of malate at night. This they turn into ATP and NADPH during the day, with their stomata closed. It’s a far less efficient way to provide energy for the plant than the photosynthesizing in our woods, which is why desert and other succulent plants grow so slowly.

In addition to helping maintain the appropriate levels of oxygen and carbon dioxide in our fragile atmosphere, plants nourish themselves and the entire living world. We breathing creatures are carbon-based life: carbon forms the backbone of every molecule in our bodies. We’re entirely dependent on plants’ ability to take the carbon dioxide from our own respiration and not only replace it with the oxygen we need but also to offer those carbon molecules to us in edible forms. That’s what allows us to make our own ATP to fuel this lovely walk among the chloroplasts. Photosynthesis is the most important biochemical process on the planet.

Pacific rhododendron (Rhododendron macrophylla) in Rhododendron Park on Whidbey Island, Washington. Evergreens can perform photosynthesis all year, but are much less efficient in winter. When cold enough, the process can shut down altogether. Photo by Betsey Crawford.

Pacific rhododendron (Rhododendron macrophylla) in Rhododendron Park on Whidbey Island, Washington. Evergreens can photosynthesize all year but are much less efficient in winter. When cold enough, the process can shut down altogether.

Given its importance, it’s no surprise that it showed up relatively early in the earth’s life. Early forms of photosynthesis are thought to have begun about 3.5 billion years ago, its various systems developing over time. Chloroplasts didn’t evolve until 2.5 billion years ago. When photosynthesis began, there was little free oxygen on earth. Early practitioners were microscopic, anaerobic bacteria, most likely using hydrogen sulfide, better known as swamp gas, to do their work. 

About 2.4 billion years ago, oxygen released by photosynthesis began to build up in the atmosphere, leading to what is known as the Great Oxygenation Event. The existing bacterial species weren’t adapted to it and began either to die out or find their way to anaerobic environments. With the evolution of mitochondria, which essentially use oxygen the way chloroplasts use carbon dioxide, species were able not only to adapt but to harness a much stronger energy source. Fueled by this huge boost to metabolism, life on earth blossomed into ever more diverse and complex life forms and ecosystems.

Salmonberry (Rubus spectabilis) in Brandywine Provincial Park, British Columbia by Betsey Crawford

Salmonberry (Rubus spectabilis) in Brandywine Provincial Park, British Columbia

Besides our dependence on plants, there are a lot of wonderful connections among us. We all inherited our carbon from the very beginning of the universe, when the first particles coalesced into mighty mother stars who, with their enormous heat and compression, made the elements that form every subsequent thing. When we give a baby a fresh string bean to munch on, we’re watching 13 billion-year-old carbon join forces in ever new forms.

We share up to 25% of our DNA with plants, remnants of our ancient, shared bacterial ancestors. Mammalian hemoglobin and plant chlorophyll have the same chemical composition, though where hemoglobin is built around iron, chlorophyll uses magnesium. When we eat chlorophyll, it helps hemoglobin with its work of cleansing and strengthening our blood and increasing oxygen uptake. Chloroplasts and the mitochondria we share with plants have a similar history. Each formed when separate species of bacteria found it so worthwhile to join forces that they’re still at it, one cell inside the other, all while wrapped in their own membranes and keeping their separate DNA. Perhaps the most successful mergers of all time. Both make ATP — adenosine triphosphate — the fundamental fuel of the breathing planet.

Ferns in this woods in British Columbia catch the last light of day. Photo by Betsey Crawford

Ferns in this woods in British Columbia catch the last light of day.

Evolution has no need to keep inventing the wheel. If the DNA we inherited from those ancestral bacteria still work, great! If the methods of producing energy work for plants, why not animals? The same plans get reused, with some evolutionary tinkering. Because our building blocks came from those ancient mother stars, people like to say that we are stardust. Via photosynthesis, we are sunlight. Between the systems we inherited from and share with plants and the fact that they ultimately become part of every cell in our bodies, you could also say we’re recycled plants. An idea that, while not quite so lofty, thrills me no end.

It’s all a marvel. I breathe out carbon dioxide and it’s returned to me nicely packaged in carrots, apples, beans, sweet potatoes, squash. Amazing! The history is stunning, all the way back to the carbon formed at the beginning of the universe. We owe thanks to photosynthesis, and its introduction of atmospheric oxygen, for all the blooming, breathing life everywhere on the globe. We owe it every minute of our lives, every thought we have, every bite we eat, every breath we take, every flower and creature we treasure. I love the science that explores and tracks and theorizes about how this fascinating process operates. But ultimately, we are left with wonder. The whole parade is one miracle after another.

Blue clematis (Clematis occidentals) in Waterton Lakes National Park, Alberta, Canada by Betsey Crawford

Blue clematis (Clematis occidentals) in Waterton Lakes National Park, Alberta, Canada

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