TTLA-2

The Land Invasion was really an Invasion of the Air!

	Soil Microorganisms including Algae Inhabit Soil Water and are thus Aquatic.
	Ancestral organisms which were (are) Flat sheets of cells relied on free surface moisture (Semiaquatic) & become moribund when dry.

Extremely Thin,Translucent Thalli of a Liverwort. These rely on free surface water and dry quickly otherwise.

NostocNodulesCropHueLab.jpg (33078 bytes)

Nostoc a Cyanobacterium can form nodules on wet soil. However, they produce a hydrophilic matrix which holds onto water tenaciously. Consequently the Cells of the filament are still in an Aquatic Environment. The small nodule has the diameter of a penny.

Nostoc and many other Cyanobacteria fix atmospheric Nitrogen. Since N is usually a limiting element in terrestrial habitats, the N fixed by Cyanobacteria was (is) extremely important for the conquest of the land.

Erect Sporophyte of a Liverwort: A small step up for Plantkind

This extremely large & complex Ponderosa Pine grows in a very dry environment.

Elevated structures confront the cold, cruel Atmosphere

	Water Molecules in the atmosphere are greatly diluted by Nitrogen & Oxygen.
	Unprotected Plant Cells are readily desiccated & die!

Dendroalasia is a Complex Moss. However, it has no way to prevent water loss from its "Leaves". This is its appearance when it is hydrated. Photo by Karen Renzaglia

This is also Dendroalasia but in its dry state. Some organisms can tolerate extreme desiccation and can "revive" following hydration. Such plants are virtually aquatic! Photo by Karen Renzaglia

The Land Invasion was really an Invasion of the Air!

Soil Microorganisms including Algae Inhabit Soil Water and are thus Aquatic.

Ancestral organisms which were (are) Flat sheets of cells relied on free surface moisture (Semiaquatic) & become moribund when dry.

Elevated structures confront the cold, cruel Atmosphere

Water Molecules in the atmosphere are greatly diluted by Nitrogen & Oxygen.

Unprotected Plant Cells are readily desiccated & die!