The Big Ordovician Freeze
Little Plants Take the Stage
Published in The EarthSphere Blog
Prologue
We dwelt upon the Ordovician in our last Forgotten Origins article. Part of the Ordovician story tells a tale of how life dragged itself onto dry land after 4 billion years, and the consequences of this invasion.
Non-Vascular Plants
Life crept out of the oceans and onto dry land about 470 million years ago during the Ordovician Period. If you’re imagining dappled sunlight dancing across the floor of a lush, primordial jungle teeming with tall, exotic trees and shaded by a thick canopy of leaves, you are wrong. Instead, picture a Martian-like landscape covered by rocks, boulders, and fine dust. But when you inspect more closely, small insignificant-looking plants appear, growing from the crevasses and on the boulders. The ancient ancestors of moss and liverworts covered the Ordovician landscape. The first Ordovician plants were simple non-vascular organisms, but they had a major impact on the world.
Mosses, hornworts, and liverworts are all examples of non-vascular plants. They grow close to the ground with shallow root systems that could never support a larger plant. Since they are non-vascular, their size is also limited by their inefficient internal transport…
