ORIGIN OF PLANTS 
The air was still very moist, covering the en- 
tire earth with a permanent fog and a uniform 
temperature. It is said that certain present-day 
islands in the Pacific Ocean approximate these 
ancient conditions. 
All the plants of that time were flowerless, 
and belonged to neither the monocotyledonous 
nor the dicotyledonous classes, which include 
the greater number of families today. ‘Thanks 
to many excellent speciments found in coal 
mines, it is possible for scientists to classify as 
many as five hundred families. It is believed 
that coal itself was mostly formed from small 
plants, but often entire trunks of the tree-like 
forms are found in bituminous strata. Bits of 
bark, cones and petrified leaves have also been 
unearthed at different times. 
In the course of evolution, the Conifer trees 
were the next to develop extensively. They 
gained a great ascendency, but were succeeded 
by Palms, Alders, Cypress and Elms. By the 
Miocene period, all the forms known in tropic 
Africa today had come into existence, but were 
restricted by no such regional limitations as they 
labour under now. Oaks and Palms, Birches 
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