8o 



The 



Large portions of the rich coal deposits 

 of Pennsylvania are the remains of these 

 ancient fernlike plants. And in those past 

 ages, two small inconspicuous relatives 

 of the fern also grew as tall trees, the 

 chib moszes and the horsetails. 



The club mosses are also commonly 

 called ground pines. Thev are creeping 

 plants that grow close to the forest floor. 

 It is difficult to say which name is least 

 fitting since they are neither "mosses" 



Living Things of the Earth unit i 



nor "pines." They are closely related to 

 the ferns. Another common name for 

 the horsetails is scouring rush (Figure 

 104). All the species included in this 

 division or phylum have true roots, stems, 

 and leaves, but they never bear flowers 

 and they never produce seeds. 



If specimens are available, you should 

 now be able to do Exercise 6. The whole 

 class might \\ ell make a common project 

 of Exercise 7. 



Plants with Flowers and Seeds 



PHYLUM - SPERiMATOPHYTES 



Characteristics of flowering plants. The 



plants of this, the fourth large division, 

 not only produce flowers and seeds but 

 they have another characteristic which 

 is not possessed by any of the simpler 

 plants except the ferns: they have well- 

 developed roots, stems, and leaves. There 

 is great variety in the size and appearance 

 of these parts, as well as in the blossoms, 

 as you can imagine when you learn that 

 there are more than 125,000 different 

 species in this division. They are the 

 commonest land-living plants. But some 

 grow in water. In fact they may be found 

 in almost any environment. Some have a 

 stem that is soft, grows rapidly, and dies 

 at the end of the year. They remain small 

 and are called herbs. Others have stems 

 that are woody and tough. If the\' have 

 one main stem, they are trees; if they 

 h;nc several equall\- thick stems arising 

 from the ground, in which case they 

 iisualK do not grow very tall, they are 

 called shrubs. 



Flowering plants vary, too, in kngili 



of life. Those that start from seeds, grow, 

 produce flowers and seeds and then die 

 during one growing season are called 

 ammals. Examples are the crabgrass, com- 

 mon as a weed in many lawns; radishes, 

 tomatoes, and lettuce of the garden, and 

 farm crops such as oats, corn, and buck- 

 wheat. Plants that start from seeds during 

 one growing season but produce flowers 

 and seeds and then die during the next 

 season are called biennials. Many weeds 

 are biennials. Among the farm and gar- 

 den crops that are biennials are winter 

 wheat, cabbage, and carrots. You M'ill 

 note that both annuals and biennials die 

 after flowering. The other seed-pro- 

 ducing plants are called peremiials. These 

 plants may live for many years, produc- 

 ing flowers and seeds each growing sea- 

 son. All of our trees and shrubs are 

 perennials as arc certain garden and farm 

 crops such as asparagus, sugar cane, and 

 tulips. Perennial grasses make the finest 

 lawns. Perennial plants may live to a great 

 age. The cypress of Mexico and some of 

 the big trees (sequoias) of California 

 ha\e lived for 3000 to 4000 years. 



