jurassic

carboniferious

the carboniferous period was a time when there was a lot of oxygen in the air .

But what made the oxygen in the air, also animals could grow to a massive size

so when they died there was a lot of rich soil wich is great for plants to grow in.

so plants made the oxygen and thats how it went for a few million years.

It's also the time when most plants evolved.

Conifers were the dominant land plant during the Jurassic period. Other land plants included Ginkgophytes, club mosses, horsetails,ferns, seed ferns, Sphenopsids, Filincophyta , Cycadeodia, Ptilophyllum, and Cycadeoidea, and cycadophytes.

Flowering plants evolved about 140 million years ago, during the late Jurassic period. This development would soon change the face of the Earth

ice age

During the ice age, the same plants grew as grow today. The glaciers stopped in Southern New York, the Northern border of Ohio and along the southern borders of the Great Lakes. South of there plants grew. Plants simply grew more to the south than they do today. The North Woods started at the edge of the Glaciers. Then came the firs and the maples. Most of South Florida would not have been tropical but subtropical. It would have had a few tropical islands where freezes would be rare. They would have reseeded South Florida with tropical plants at the end of the Ice Age. Cuba would have been Tropical. Birds from Cuba came to the Florida Keys after the end of the Ice Age.
So, as the ice melted, the plants of today moved north. The children of the ice age plants found the best places for them to grow and prosper. It was as if the plants moved into the area best suited for them.