Cyanobacteria: R-E-S-P-E-C-T

We owe cyanobacteria our respect. And they might deserve our fullest gratitude as well if it weren’t for one nasty trait.

For starters, if we are to believe that our elders deserve respect, cyanobacteria certainly qualify. They date back 3.5 billion years, almost to the earliest signs of life. But they are not only old. They are interesting, they seem uncomplicated, and they are powerful and successful. They are single-celled, though many live connected to each other in colonies and filaments. They are primitive; unlike the cells of younger species, they have no nucleus. And they have not only survived all this time; they have thrived. Their species number at least two thousand that have been described and at least twice that number in total. Most are blue-green—“cyan”—but their various pigments also account for the colors of pink flamingoes and the Red Sea.

cyanobacteria (


Cyanobacteria gave us oxygen—and continue to do so. For the first two billion years after the earth’s formation 4.5 billion years ago, the atmosphere contained almost no oxygen. But the blue-green pigment in cyanobacteria is a mix of green chlorophyll and a blue pigment both of which turn sunlight and carbon dioxide into sugary energy for the cell. Oxygen is the waste product—and early cyanobacteria produced so much of it for so long that it accumulated in the atmosphere and eventually supported larger, more complex cells, including ours.

Just as important, atmospheric oxygen spawned an ozone layer that reduced the lethal levels of the sun’s ultraviolet radiation. It’s that filtering that allowed early plant and animal life to finally move on to land after three billion years in the water.

Cyanobacteria made plants themselves possible by becoming part of them. Some other early bacteria engulfed cyanobacteria and then, because of cyanobacteria’s efficient energy production, turned them into one of the pieces of organic machinery enclosed within a plant’s cell. We see them today as the greenery of plants—the chloroplasts—that power them and keep them reaching for the sun.

Cyanobacteria are handy with another gas in addition to oxygen. They convert nitrogen in the atmosphere into a form that plants and animals need for such building blocks as proteins and DNA. Natural nitrogen fertilizer.

pond scum wikipedia


Cyanobacteria often go by the name of blue-green algae. But they’re not algae. Algae is an informal term for many water-borne organisms that contain  chlorophyll but lack stems, roots, or leaves. Seaweed is algae. Cyanobacteria are bacteria—simple cells, often strung together, without nuclei.

As for that one nasty trait, cyanobacteria can kill you. Especially in freshwater ponds and lakes, blooms of cyanobacteria looking like blue-green paint slicks may be toxic to nerve and liver systems, depending on the species. The poisons may work their way into the food chain, pets may eat them, water-skiers may absorb them. The result can be respiratory failure, Parkinson’s, ALS. Not often, but too often. Respect.

Reading about cyanobacteria on the Internet, you get a glimpse of a life-form from an inconceivably ancient world that is woven throughout the air, water, and soil of our own time. We are in their debt for the breath we take, the food we eat, for our living on solid ground.  We stand on their countless, tiny shoulders.

Jahren’s ‘Lab Girl’: The Dramatic Life of Plants

Much as people admire plants, it is difficult to relate to them. It takes a special focus to sympathize with a plant’s struggles, to identify with it, to understand its idiosyncrasies. We have an immense range of words and images for capturing our own inner experiences—fear, exhaustion, revulsion, joy, thirst and so forth—but a mere handful for even the most prominent stages of plant life—growing, blooming, wilting, and a few others. This distance isn’t surprising. Plants are different from us in basic ways. They are anchored to the ground, they don’t have faces, and they make their own food. We acknowledge them as members of the family of life, but they also seem alien.

The poverty of our understanding of plants contributes, I believe, to our uneasiness about the meaning of our lives. We’re prone to feeling that being alive is either an exclusively human pleasure or a lonely human struggle. It’s easy to lose touch with the reality that plants along with animals have been passing through the experiences of growing, struggling, fending off threats, and sometimes flourishing, for hundreds of millions of years and by the billions. We might feel more at home in our own skins if our imaginations could take in the  lives of plants a little more easily.

Hope Jahren helps us do so. Lab Girl, her memoir, traces her life through the rigors of becoming an established research scientist and her workaholic triumphs and disappointments in labs and in the field. The bristling autobiographical chapters alternate with brief essays about how plants function and survive. It’s these plant chapters that most caught my attention. Here are excerpts:

      No risk is more terrifying than that taken by the first root. A lucky root will eventually find water, but its first job is to anchor—to anchor an embryo and forever end its mobile phases, however passive that mobility was. Once the first root is extended, the plant will never again enjoy any hope (however feeble) of relocating to a place less cold, less, dry, less dangerous. Indeed, it will face frost, drought, and greedy jaws without any possibility of flight. ….The root grows down before the shoot grows up, and so there is no possibility for green tissue to make new food for several days or even weeks. Rooting exhausts the very last reserves of the seed.  The gamble is everything, and losing means death. The odds are more than a million to one against success.
But when it wins, it wins big. If a root finds what it needs, it bulks into a taproot—an anchor that can swell and split bedrock, and move gallons of water daily for years.  (52)

     A cactus doesn’t live in the desert because it likes the desert; it lives there because the desert hasn’t killed it yet. Any plant you find growing in the desert will grow a lot better if you take it out of the desert. The desert is like a lot of lousy neighborhoods: nobody living there can afford to move…. A desert botanist is a rare scientist indeed and eventually becomes inured to the misery of her subjects. Personally, I don’t have the stomach to deal with such suffering day in and day out.   (142)

     Here’s my personal request to you: if you have any private land at all, plant one tree on it this year. If you’re renting a place with a yard, plant a tree in it and see if your landlord notices. If he does, insist to him that it was always there….
Once your baby tree is in the ground, check it daily, because the first three years are critical. Remember that you are your tree’s only friend in a hostile world. If you do own the land that it is planted on, create a savings account and put five dollars in it every month, so that when your tree gets sick between ages twenty and thirty (and it will), you can have a tree doctor over to cure it, instead of just cutting it down….
At the end of this exercise, you’ll have a tree and it will have you. You can measure it monthly and chart your own growth curve. Every day, you can look at your tree, watch what it does, and try to see the world from its perspective. Stretch your imagination until it hurts: what is your tree trying to do? What does it wish for? What does it care about? Make a guess. Say it out loud.    (282)

It would be easy to characterize this writing as merely heavily personified and emotional. But I take these and other passages as capturing realities about plants that rarely come within our understanding, empathy, or language. Most people would be more likely to imagine what it is like to be on the moon than what it like to be the tree in the backyard that is bracing for winter. And if we think of our human emotions—such as terrified and enjoy— as reactions to situations and not just shifting moods, then a first root really is a terrifying gamble, plants really can be said to enjoy, to benefit from, their mobility as seeds that might find friendly ground, and they really do get exhausted when their physical necessities run short.

And then there’s “you’ll have a tree and it will have you.” Considering the world’s deteriorating environment, Jahren argues, if one tree can rely on you, that tree is well off. I would add that the benefit is mutual; we ourselves are better off if we can share and feel, even faintly, the life of any plant.

Stem Cells: How To Build and Maintain Bodies, Including Plants

Until recently, I didn’t know much about stem cells except that they produced other kinds of cells and that the medical research on them was controversial. In the context of the history of life, it turns out, their importance is as fundamental as you can get.

It took more than a billion years for the first cell with a nucleus to come together. Since then, the only reliable source for a new cell has been another cell. Every cell is an offspring. True for plants as well as animals.

An embryonic stem cell (Wikipedia)

An embryonic stem cell

But while cells are specialized for one task or another, they are not always very good at dividing and reproducing. Muscle cells, blood cells, and nerve cells don’t reproduce at all. Other cells in the body divide only under some circumstances or only a limited number of times.

But reproduction is the stem cell’s specialty. When it divides, it produce another stem cell, ready for the next round, along with a muscle cell or blood cell or nerve cell or a cell of another organ. It looks the part for such flexibility—blob-like, unstructured, not committed until needed.

Stem cells are stationed throughout the body, small groups of them in each organ, like local hospitals on call to repair the sick and damaged. They are a profound piece of bodily engineering, a design for the long-term, like a futuristic car that carries little 3-D printers throughout the engine and chassis to create new parts and replace the old parts automatically.

In human embryos, in contrast to adults, stem cells literally build the body. When an embryo is only a few days old, its stem cells begin to form all—all—of the specialized cells needed in a body, some 200 of them.

In this root tip, the number 1 marks the relatively unstructured stem cells in the meristem. (Wikipedia)

In this root tip, the number 1 marks the relatively unstructured stem cells in the meristem.

Plants have stem cells too. Located near the tips of the roots and stems in a layer called the meristem, plant stem cells divide into both specialized cells for the plant and additional stem cells. Stem cells are, in other words, the place where a plant grows.

One of the wonders of any living thing is the sheer variety of its parts, the inventory of its tubes, organs, fluids, surfaces, protrusions, electric circuits and rigid pieces. As we pause to appreciate this profusion, sing the praises of the smudgy cell that creates and repairs them all.