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A tiny fern with a big secret just got into the Guinness Book of World Records

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A tiny fern with a big secret just got into the Guinness Book of World Records

Tmesipteris oblanceolata is an obscure species of fork fern found in New Caledonia, a French territory in the South Pacific. Just 4 to 6 inches tall, the humble plant is, in one particular way, the most remarkable living thing in the world.

“You would walk over it. You might even tread on it without knowing it,” said Ilia Leitch, a plant evolutionary biologist and senior research leader at the U.K.’s Royal Botanic Gardens, Kew. “But it houses within it this great secret.”

Recently, T. oblanceolata entered the Guinness Book of World Records after a team of scientists determined that the wispy fern has the biggest known genome of any living organism. Crammed into the nucleus of every one of its cells are 160.45 billion base pairs — 160.45 billion rungs on the twirling double-helix ladder that is the plant’s DNA.

T. oblanceolata has more genes than the mighty California redwood (Sequoia sempervirens) or the massive blue whale (Balaenoptera musculus). It has 50 times more DNA than Homo sapiens, the species that figured out what DNA is in the first place. The findings were published in the journal iScience.

“We were absolutely astonished when we found out how big this genome was,” said botanist Jaume Pellicer of Institut Botànic de Barcelona in Spain, a co-author of the study along with Leitch. “We already knew about the existence of giant genomes in the genus but did not anticipate that the one in Tmesipteris oblanceolata was going to beat any previous records.”

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A genome contains all the information cells need to direct the growth and development of the organism. But life doesn’t offer up instructions in the tidy, more-steps-equals-more-complexity way of Ikea or Lego assembly manuals — hence petite ferns with jumbo-sized genetic codes.

A fern with tiny yellow seeds
A view of fern fronds

You might step on T. oblanceolata “without knowing it,” a plant evolutionary biologist said. (Photographs by Pol Fernandez and Oriane Hidalgo)

Measuring genome size is “not a way to measure genome complexity or coding capacity,” said Elliot Meyerowitz, a Caltech biologist who was not involved in the research.

Only a minuscule sliver of the genetic material that most plant and animal cells lug around actually contains direct instructions for how to make the building blocks that make up living things. Less than 2% of the human genome actually codes for proteins. For the fork fern, the research team estimates that less than 1% of its genome does.

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The rest is known as noncoding DNA. Understanding what that noncoding genetic material does and why cells haul it around are among the biggest questions in evolutionary biology.

Half a century ago, scientists dismissed this noncoding stuff as “junk DNA,” a term now considered “a reflection of our own ignorance,” Leitch said.

It’s not that it all does nothing, she said. We just don’t yet understand everything that it does.

T. oblanceolata ferns grow amid tangled branches and fallen leaves.

T. oblanceolata ferns grow amid tangled branches and fallen leaves.

(Jaume Pellicer)

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In recent years, researchers have found that manipulating or deleting some of these noncoding sequences affect gene expression. This suggests that at least some of this material plays a role in the processes that “switch” genes on and off, “like the conductor of an orchestra, saying who comes in here and who should be quiet here,” Leitch said.

This intricate choreography of gene expression is how we get the incredible diversity within our own species and across the kingdoms of living things.

“Understanding how these genomes function and are structured represents the ultimate milestone in this field of research,” Pellicer wrote in an email. “But for now, it is like trying to read a book of instructions without even knowing where page one is!”

T. oblanceolata displaces the previous genome record holder, a modestly sized flowering plant called Paris japonica that has 149 billion base pairs. While there may be something else out there packing a bigger genetic punch, botanists believe these plants are at the upper end of how much DNA a living thing can have.

A man in a jacket next to a tree, surrounded by ferns and other foliage

A researcher looks for fork ferns in New Caledonia.

(Oriane Hidalgo)

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“If it’s not the biggest, it’s jolly well close to it,” Leitch said of the fork fern’s genome. “There are so many consequences associated with having so much DNA that I think we’re at the limits of what biology can cope with.”

An organism has to divide its cells in order to grow, and before it can do that it has to make a copy of all the DNA in its cells. Copying a colossal genome is a big investment of time, energy and nutrients, Leitch pointed out. For plants, bigger genomes are associated with slower growth and less efficient photosynthesis.

As a result, organisms with massive genomes tend to be found in stable environments without much competition, Leitch said. That’s true of T. oblanceolata, slow-growing Paris japonica and the marbled lungfish, holder of the animal kingdom’s largest genome (nearly 130 billion base pairs).

Unfortunately for T. oblanceolata, stable conditions are increasingly hard to come by in a rapidly changing climate.

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“As long as they’re stable, as long as things don’t change, selection won’t weed them out, so to speak,” Leitch said. “I would predict that if the environment changed, they would not be in a good position.”

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Science

Test Your Focus: Can You Spend 10 Minutes With One Painting?

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Test Your Focus: Can You Spend 10 Minutes With One Painting?

You made it , longer than about percent of readers so far.

The Painting

As you may recall, the painting you just spent time with is “Nocturne in Blue and Silver,” by the American artist James McNeill Whistler. (You may be familiar with one of Whistler’s more famous paintings — a portrait of his mother.)

The one you just spent time with currently hangs on the second floor of the Harvard Art Museums:

Lauren O’Neil for The New York Times

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The painting, part of a series that Whistler started in the late 1860s, shows the industrial banks of the River Thames in London in hazy blue tones.

In an 1885 lecture on the interaction between nature and the artist, Whistler spoke of the transition from day to night, “when the evening mist clothes the riverside with poetry as with a veil, and the poor buildings lose themselves in the dim sky, and the tall chimneys become campanili, and the warehouses are palaces in the night.”

That mark we just saw is Whistler’s “signature,” and we see a version of it in many of his paintings. It is derived from the form of a butterfly; he iterated on the symbol throughout his life.

And the second reflection? Well, this is where things get fun. You may crave a definitive answer, but the painting itself doesn’t really provide one.

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Kate Smith, a senior conservator of paintings and head of the paintings lab at the Harvard Art Museums, has looked at infrared photographs of the painting. She has a theory of her own.

She believes Whistler may have started the painting one way and then simply changed his mind, flipped the panel upside down and started over.

Ms. Smith explained that this mystery reflection could be what’s called a pentimento — a change to a piece of art that slowly emerges over time. It’s possible that when this painting was finished, this reflection wasn’t there — by design. It may have emerged only decades later.

Or Whistler may have intentionally left the ghostly reflection in for us to see. He described the paintings in this series as arrangements of “line, form and color first.” Once, he was asked to confirm if figures in another painting were people. He wouldn’t say one way or another.

“They are just what you like,” he said.

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(If you want, look again now that you know more.)

The Point

This painting was well suited as a subject of our experiment: It has mysteries revealed upon close inspection. But the point of the exercise was not exactly for you to notice the mysteries. It was just to get you to notice at all.

The act of focusing is both possible and valuable, researchers say, no matter how intimidating or pointless it might seem. That’s particularly important in a world where typical office workers spend an average of less than a minute at a time on any one screen, according to research by Gloria Mark, a professor at the University of California, Irvine, and author of “Attention Span.”

When you’re used to a manic social media feed, “it’s hard to pay attention to content that doesn’t change,” she said.

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Think again about the time you spent looking at the painting.

At first, you may have felt that it was too dull to hold your interest for even 10 seconds, much less 10 minutes.

When Professor Roberts at Harvard first conceived of this assignment — the three-hour version — she saw it as a launching point to help students write an art history research paper. But these days she also sees it as a way to teach patience. (She recommended this Whistler painting for our exercise.)

Many of her students, she says, react to the assignment with “horror.” (This may have happened to you, too.)

“It’s a combination of, ‘Oh, my God, that’s impossible,’” she said. “And also at the same time, the sense that it’s remedial.”

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But they usually find the experience, as you may have, neither too difficult nor too simple. The students see that they did not notice everything worth seeing in the painting at first glance, she said. And they find that by being a little bored, and a little outside their comfort zone, they can see something new.

If you liked the way you felt, try the exercise again with any piece of art. Or, if you’re feeling bolder, print out Professor Roberts’s original assignment. Then go to a museum, pick a work of art and settle in.

Consider also a song, or a poem. Or skip art altogether.

“You can just go look at a tree,” she said. “You can look at a rock.”

Your attention is a product of a lot of things, said Professor Mark, not all of which are in your power. But a little practice can help. “We do many behaviors that are automatic,” she said. “Becoming aware of such automatic behaviors is a skill, and we can then better control where we place our attention.”

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And with that skill honed, you may linger more, and better.