SUMMARY 309 



cypress, mangrove, magnolia, mahogany, and live oak 

 abound, and the forests are dense with climbing plants 

 and air plants. 



Some of the most interesting ways in which plants 

 adapt themselves to their surroundings are seen in dry 

 climates like our western deserts. The greatest problem 

 of plants under these conditions is how to get the most 

 water, and how to lose the least. As a result they have 

 large and widely spreading roots, a thick skin, and a 

 small surface of leaves. The cactus (Fig. 252) is an 

 example of such plants. Its leaves are modified to spines, 

 because it does not need ordinary leaves; and the plant 

 body is a compact mass, so that there is little evaporation. 



330. Summary. The organs of a plant are its roots, leaves, flowers, 

 etc., each of which has some particular function, or duty. 



The two general functions of all living things are nutrition and re- 

 production. 



The conditions and surroundings of an organism are its environ- 

 ment. The influence of the environment is a stimulus to the organism ; 

 the change or action in the organism is its response to the stimulus. 



Germination is the change from seed to seedling. 



The seed of a bean consists of testa and embryo. The embryo con- 

 sists of two cotyledons, a hypocotyl, and a plumule. Nutriment stored 

 in an embryo, outside of the cotyledons, is called the endosperm. 



Monocotyls have only one cotyledon. 



Leaves consist of blade, petiole, and sometimes stipules. Veining 

 may be palm-, feather-, and parallel-veiumg. A compound leaf has 

 several leaflets. Leaves may be alternate, opposite, or whorled. 



A leaf is covered with epidermis, through which there are openings 

 called stomata. Leaf tissue consists of cells. Cells contain proto- 

 plasm, and, in green leaves, stems, etc., chlorophyll. 



The leaf is the laboratory of the plant. In it carbon dioxide and 

 water are built up into carbohydrates, and oxygen is set free. 



