Going to Ground

Going to Ground, becoming Terrestrial.
There is a sense with many commentaries that somehow the aquatic ancestors (eg tetrapods) just plopped on the the land and somehow survived and evolved. And somehow it all came together in the great Explosion..but how?

Plants have adapted from wet conditions to dry, at least occasionally. Some of the adaptations of plants to a terrestrial existence include a waxy cuticle, surface pores (stomata) that enable gas exchange, & protected reproductive structures See below for more adaptations for life on dry land. Up till now, plants had grown in constant/continuous water. What happens when they come to the dust? It is now the plants needed a root system to support the overground vascular structure that could grow so much bigger, with ever more differentiated parts – compared to ferns and bryophytes. The root world with mycorrhiza and surrounding biosphere would have been crucial to make the vascular system function in getting water to the top of bigger plants

From Earthlink. Land, Plants and Diversity explain what is need by the plants to deal with drier conditions..on earth.

Problems Solutions
Minerals in the soil and water Roots
lack wax and chlorophyll
have large surfaces area (aided by Mycorrhiza fungi)
have vascular tissue for conduction of food and water
Light and CO2 in the air Leaves and Stems
have waxy coverings to prevent water loss
chloroplasts can move to obtain the best arrangement for absorption of light
turgor pressure prevents wilting
stomata regulate water loss and CO2 absorption
Gravity
Prevents vertical growth Lignin
Reinforces cellulose. This skeletal support allows turgor pressure to increase to help maintain rigidity.

Increase in Height

Requires mechanisms to prevent water loss and conduct water more effectively Vascular Transport System

Allows plants to grow taller in order to reach light. The vascular system is made of microscopic pipes, the xylem and phloem. Xylem is lignified adding to the other supporting tissues.

The transition to drier conditions requires many of these plant systems to evolve together, and each requires an essential element - all of which are found in volcanic ash.
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