Understanding 425 Million Years of Plants Through Phylum Rhyniophyta

If you magnify a leaf a thousand times you’ll find a sea of chloroplast uniformly ushering in the direction of light. This motion is the beginning of photosynthesis. The moment that plants learned how to harvest light, they gave birth to our atmosphere.

Science teachers across the globe have lectured on the impressive causation— plants use hydrogen to grow and dispose of oxygen as a ‘waste’ product. Next, oxygen creates an ozone layer, which envelops our planet and shields it from the Sun’s harmful rays. This in turn makes our planet hospitable to humans, but long before that, it enabled plants to move from water to land for the first time in history.

A stone wall outside the village of Rhynie, in northeast Scotland, contains the best evidence of the leap that plants made over 425 million years ago.

Fossil remains of the first known vascular plant, phylum rhyniophyta, swirl throughout the rock displaying symmetrical stems and upright axes’ that once grew to be 18 cm tall. When polished, the fossil looks similar to the inner canal of an oyster shell with a history of grooves far more complex than what meets the eye, at least at first glance. This mid-Silurian era plant survived with numerous branches and aerial axes, serving as the plant’s photosynthetic organ until plants evolved and developed leaves 380 million years ago.

While it was unable to produce flowers or seeds, evidence suggests that Rhyniophyta were homosporous. They gave life to a single type of spore– similar to ferns– each with the ability to germinate and create egg cells receptive to sperm, which furthered their lifecycle. This was only the evolutionary beginning of plants boasting their skill-sets, as they would soon develop roots and cover continents, forming extensive forests and bearing seeds.

Today, Scotland has a unique geography and even more interesting topography, with 11,000 km of coastline, mountains, islands, canals, and rivers. But it wasn’t always this picturesque: it use to be rocky and barren, south of the equator, with sizzling hot springs, much like the rest of our Earth.

Oxygen enabled the country to grow rare alpine plants, award-winning gardens, and blankets of low-lying flowers. This began with phylum Rhyniophyta and ancient microbes that used the Sun’s rays to harness the molecule chlorophyll, a photosynethic pigment that absorbs blue and red wavelengths in order to reflect the green hues that make plants recognizable.

Plants have chosen for the world around us to be green and so it is. Plants have chosen to omit oxygen and so we live to see another day. Take a moment to pause, inhale rich oxygen, and think about the incredible cycle of life that plants have been responsible for throughout our geologic history. They will only continue to grow and amaze us if we allow them to.