Pteridophytes have evolved to fill almost every ecological niche but the greatest species diversity is clearly found in the tropical rainforest. The rapid disappearance of this biome throughout the world with many of their pteridophyte species yet undiscovered, let alone described, is of great concern.

Nature is unable to repair the extensive injury.

We traveled down under for our vacation.

But, 30 percent of obese patients don't respond to this increased drive; their breathing muscles become fatigued and they underbreathe.