PLANT LIFE IN OKLAHOMA. 55 



Indian Plantains, common groundsel, butterweed, ragworts, squawWeed, 

 common burdock, thistles (5), American starr thistle, chiokory, dwarf 

 dandelion (3), false dandelion, common dandelion, sow thistles, including 

 the spring sow thistle and Tab>bit lettuce, wild lettuce (8), rattlesnake 

 root, white lettuce, and hawkweeds (3). 



TREES AND SHRUBS. 



Par back in geologic history we find the records of tree growth. 



Our coal beds are the products of abundant growth of vegetation, 

 consisting in a large part of trees, many of which reached large propor- 

 tions. Fossil leaves, plants, and twigs in the shales and sandstones, and 

 .the silicified trunks of trees commonly found bear out the extensive 

 growth of trees in times past. 



Within recent times the greater part of the land surface of the earth 

 has been covered with forest growth. At the present time trees are 

 among the most conspicuous obg'ects of nature. It has been estimated 

 that the aggregate original area of the forests of North America was 

 about 850 million acres. This original area has been reduced until not 

 more than 550 million acres remain, and a large percentage of this is 

 not to be considered in the area of the economic timbered region. 



A tree is usually defined as a plant with a single trunk of woody 

 structure that does not branch for some distance above the ground. Woody 

 plants that branch directly above the soil, although they grow to a 

 height of 20 feet or more, are called shrubs or bushes. Certain shrubs 

 may be made to grow treelike, and some plants which are shrubs in the 

 northern states grow as trees of considerable size farther south. 



A tree consists of three parts; first, the root; second, the branch or 

 stem; third, the crown. The root extends into the ground from a few 

 inches to several feet, according to the variety of tree, character of soil, 

 and the moisture conditions. The trunk or stem supports the crown and 

 supplies it with mineral food and water from the roots. The crown con- 

 sists of a network of branches, buds, and leaves. The mosit important 

 processes in the growth, reproduction and nourishment of the tree, take 

 place in the crown. 



Trees and shrubs as they stand together on some large area whose 

 principal crop is trees and shrubs constitutes a forest. However, a forest 

 is far more than a collection of trees. It has a population of animals and 

 plants peculiar to itself, a soil largely of its own making, and climatic 

 conditions differing from those in the open country. The forest pre- 

 vents floods, influences rainfall, supplies fuel, timber, and food. 



But with all the good that the forest has been to man its real value 

 has not been considered and it has been recklessly used and ruthlessly 

 destroyed. 



The United States is divided into several forest regions. A single 

 unbroken forest belt — the spruce forest of Canada, extends across North 

 America. * (1) A part of this belt extends within the borders of the United 

 (1) Bowman, Isaac, Forest Physiography, p. 133. 



