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Uncovering how plants took over the land

Next time you see a branch don’t take it for granted. It was this simple structural addition to the first ever land plants that allowed them to thrive and colonize land.

BBSRC-funded Dr Jill Harrison and her lab are uncovering the secrets behind how branching structures evolved by inducing branching in mosses.

The image at the top shows an unbranched moss shoot with a reproductive structure at the tip.

The first land plants that appeared on earth about 450 million years ago had tiny bodies with a single reproductive shoot much like this plant.

The image below shows the same type of moss with a branch point.

The overall shape resembles the earliest branching plants which were tiny, but had a branching form that now only exists in ancient plant fossils.

Once plants learned how to branch, they were able to partition the roles of different branches on each shoot.

This allowed some branches to become specialised for photosynthesis, and eventually led to the evolution of leaves.

Jill and her team were able to induce a branching form in this plant by a simple change in hormone distribution, suggesting that the innovation of branching some 450 million years ago could have been simple.

Image credit: Jill Harrison

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Fragment from Georg Büchner’s “Lenz” [translated by Richard Sieburth]

Only sometimes when the storm tossed the clouds into the valleys and they floated upwards through the woods and voices awakened on the rocks, like far-echoing thunder at first and the approaching in strong gusts, sounding as if they wanted to chant the praises of the earth in their wild rejoicing, and the clouds galloped by like the wild whinnying horses and the sunshine shot through them and emerged and drew its glinting sword on the snowfields so that a bright blinding light knifed over the peaks into the valleys; or sometimes when the storms drove the clouds downwards and tore a light-blue lake into them and the sound of the wind died away and then like the murmur of a lullaby or pealing bells rose up again from the depths of ravines and tips of fir trees and a faint reddishness climbed into the deep blue and small clouds drifted by on silver wings and all the mountain peaks, sharp and firm, glinted and gleamed far across the countryside, he would feel something tearing at his chest, he would stand there, gasping, body bent forward, eyes and mouth open wide, he was convinced he could draw the storm into himself, he stretched out and lay over the earth, he burrowed into the universe, it was a pleasure that gave him pain; or he would remain still and lay his head upon the moss and half-close his eyes and then everything receded from him, the earth withdrew beneath him, it became as tiny as a wandering star and dipped into a rushing stream whose waters flowed beneath him. But these were only moments, and then he got up, calm, steady, quiet, as if a shadow play had passed before him, he had no memory of anything.