22 THE PLANT WORLD. 



sand species of coal-age plants lived in the United States alone. They 

 grew rapidly, as do the plants in the tropics at the present day, and 

 dropped their branches, leaves, seeds and decaying trunks into the 

 water beneath, where they were gradually transformed into the im- 

 mense deposits of coal. 



By carefully studying the fossil remains of coal-plants which are 

 abundantly preserved in the shales both above and below the seams 

 of coal, botanists have been able to determine in large measure the 

 kinds of plants that grew at that time. By the aid of the accompany- 

 ing illustration, which has been restored from a careful study of the 

 fossils, we may be for the moment transported to the interior of one 

 of these damp forests intersected by stagnant waters. In the immediate 

 foreground is a group of huge trees known as Lepidodendrons or scale- 

 trees, with rough, diamond-shaped scars and forking branches ; they 

 are two or three feet in diameter and fifty to seventy feet high. The tree 

 in the middle is dead and has lost its leaves and smaller branches and one 

 of its large branches has fallen. The living relatives of the Lepidoden- 

 drons are the little club-mosses or Lycopodiums with stems only a few 

 inches in height. 



In the background at the left and almost hidden are a number of 

 straight columnar trunks called Calamites, which are represented in 

 the present flora by the horsetails or scouring rushes [Eqnisetuin). 

 They are unbranched and are really plants of low or simple organiza- 

 tion. 



In the distance among the Lepidodendrons are a number of tree- 

 ferns which may be recognized by their tall, thin trunks and spread- 

 ing crown of graceful foliage. They are known as Pecopteris, and 

 have left no living representatives. A young stem belonging to the 

 same species is seen to the left in the foreground. 



The dead Lepidodendron has the branches covered with pendant 

 parasitic plants and the trunk bears tufts of large-leaved, fern-like 

 plants, none of which have left any close living relatives. On the ground 

 under the trees are little clusters of ferns. 



Besides the vegetation restored in the illustration there are 

 numerous strange trees with straight, unbranched trunks, sixty or 

 seventy feet high, bearing a tuft of long, narrow leaves at the top. 

 They are known as Cordaites and are evidently allied to certain living 

 conifers, such as the Ginkgo or maiden-hair tree of Japan. A great 

 number of nut-like fruits are supposed to have been the fruits of the 

 Cordaites. There were also trees with the branches covered with 

 small, sharp-pointed, stiff leaves, known as Araucarites and closely re- 

 lated to the modern Araucaria or Norfolk Island pine. 



