PLANTS MODIFIED BY THEIR SURROUNDINGS 165 



with an average temperature of over 80 Fahrenheit, causes ex- 

 tremely rapid growth. One of the bamboo family, the growth of 

 which was measured daily, was found to increase in length on the 

 average nearly three inches in the daytime and over five inches 

 during each night. The moisture present in the atmosphere 

 allows the growth of many air plants (epiphytes), which take the 

 moisture directly from the air by means of aerial roots. 



Conditions in a moist, semitropical forest. The so-called "Florida moss" is a 

 flowering plant. Notice the resurrection ferns on the tree trunk. 



The absence of cold weather in tropical countries allows trees 

 to mature without a thick coating of bark or corky material, 

 plants all having a green and fresh appearance. Monocotyledo- 

 nous plants prevail. Ferns of all varieties, especially the largest 

 tree ferns, are abundant. 



Plant Life in 'the Temperate Zones. In the state of New York, 

 conditions are those of a typical temperate flora. Extremes of 

 cold and heat are found, the temperature ranging from 30 Fahren- 

 heit below zero in the winter to 100 or over in the summer. Condi- 

 tions of moisture show an average rainfall of from 24 inches to 52 



