400 Million Years of Ferns

Ferns are all leaf, all the time—no celebrated flower, no seduction of the insect. At the tips of green sprouts, curled fiddleheads unroll while leaflets widen behind them like the wakes behind boats. My store-bought Boston fern, tended for years with no expertise, is a fountain of green, its dazzling fans of leaves arching up, out, and over.

Before ferns, plants were creatures of the water, with no need for roots or stems. But about 450 million years ago, Earth passed through the first of its five mass extinctions (so far). The climate cooled, water froze, glaciers grew, the sea level fell, coastal and ocean habitats disappeared. But new land was exposed, and when the climate warmed again, plants grew there.

The first of these land plants were mosses. Carpets of moss sprang up along lakes and streams. But without deep roots or firm stems, mosses grew no higher than a few inches. Thriving on land requires tubes that can carry liquids up and throughout an organism. Ferns were among the earliest plants with roots to dig deep for water, and with stalks and stems to transport it throughout the plant. Vascular tissue changed everything. Ferns reached the height of trees.

Devonian ferns wikimedia


And ferns grew very efficient leaves. They needed them to capture carbon dioxide whose levels fluctuated widely over the millennia. Whenever the atmosphere’s declining carbon dioxide led to cooling temperatures, the hundreds of leaves on even a small fern could soak up enough to keep it going. Today, healthy ferns withstand cold weather better than most plants.

Ferns have multiplied the world over in part because of how they propagate. They were and are old-fashioned and deliberate about sex. Instead of reproducing through miniaturized plants embodied in seeds, ferns spread through spores, single cells released from the underside of the fronds. When the spores settle on moist soil, they grow into a tiny intermediate plant that will create the male and female components for the start for a new fern. Spore propagation seems an overly complicated, two-step process, but the lightness of the spores lets them disperse on the wind and germinate on distant moist soil.

Some days I stare at a plant whose distinctive features date back nearly 400 million years. No other plant or animal that I see every day goes back almost to the beginning of life on land. A fern’s ancestors invented leaves and roots and the old method of reproducing.  They survived four mass extinctions, as well as the flowering plants that burst on the planet 125 million years ago and came to dominate the plant kingdom. Ferns watched the dinosaurs come and go. Today they regale us with tales of ancient climates and their ingenious survival skills.



Sink Or Float: The Ordeal By Water

Well-written history often reminds us that although people in the past lived differently than we do, their lives moved in many of the same spheres with many of the same motives as ours do. They managed sex, children, and an economy; they punished cheaters, criminals, and often the vulnerable; they praised those who provided for them, or promised to. Their circumstances and societies were different, but they coped with their needs and with each other in recognizable ways.

Compelling examples of this appear in Michael Pye’s The Edge of the World: A Cultural History of the North Sea and the Transformation of Europe (2015). The history traces the rich complexities of northern Europe, often neglected, during what we think of as the Dark Ages, from about 500 to 1300.


In his chapter on the gradual emergence of law, Pye describes the “trial by ordeal” that preceded trial by judge or jury. We are familiar with one ghastly version of such justice. Suspects are bound and lowered into water. If they float, they are guilty and are executed. If they sink, they are innocent, and are pulled out. The ordeal was is use for over a thousand years, early on for charges ranging from murder to land ownership claims but later and most famously for suspected witchery, sorcery, and heresy.

I’ve always thought of the ordeal by water as an outstandingly stupid method for establishing innocence or guilt. Its absurdity seems epitomized in the Monty-Pythonesque craziness that the “fortunate” person who floated was found guilty and often executed.

But as Pye vividly explains, the appeal of the ordeal was that it claimed “the direct participation of God.” The water was holy water (or was supposed to be), and if the guilty party floated it was because the holiness of the water rejected the corrupt body. God’s participation seemed essential at a time when the state provided “no judge or jury [to] sort out facts and decide who is right… and wrong.” Written archives, files, paper trails, and law books were few.

In addition, “God’s verdict is unanswerable,” an irrefutable decision at a time when everyone in small communities knew each other’s business too well. The command announced by priests at the beginning of each ordeal–“Judge not that ye be not judged”–served as a stern reminder of the community’s fallibility. But the growth of trial by law book, judge, and jury, along with the withdrawal of the Church’s approval of ordeals, gradually shifted the responsibility for verdicts from God’s hands to people’s.

For me, uncovering the thinking behind such alien customs, even the cruel ones, helps me put people from the past into the stream of history that I too am swimming in, where we all make the best of our circumstances. This is a consolation of history; we are less alone in time and more at home on the planet when we understand a little of what prompted the strange behaviors of the past.