34 



The Plant World. 



year to year is said to vary in inverse ratio to the yield of the 

 crops, as the fiber industry is resorted to for a livelihood more 

 often when other means fail. Practically all of the palma and 

 lechuguilla fiber is extracted by hand, a slow and laborious 



process. 



I wish to thank Professor Trelease for his kindness in iden- 

 tifying the plants here under consideration. 

 Desert Laboratory, Tucson, Arizona. 



BOGS, THEIR NATURE AND ORIGIN.* 

 By John W. Harshberger. 



A bog, considered from the view point of the botanist, is 

 an area wet and springy from the nature of the substratum, 

 which consists on top of living sphagnum, or bog mDsses satur- 

 ated with water. Beneath lie the compacted remains of these 

 mosses, and other plants, which form a brown or black mass of 

 vegetal detritus and this, by the weight of the overlying material, 

 is compressed into peat of various degrees of compactness. 

 Bearing in mind this definition of a bog, it appears that true 

 bogs occur only in northern temperate regions, as in Ireland, 

 portions of England, northern Germany, Nova Scotia, Canada 

 and the northern United States. Many thousands of square 

 miles are covered in Europe and North America by peat bogs. 

 About one-seventh of Ireland is bog covered, that of Allen alone 

 comprising 238,500 acres with an average depth of 25 feet. 



Transeauj has shown that the largest number of bogs are 

 found north of a line which marks the southern boundary of 

 the great terminal moraine, while the northern boundary of 

 the bog region coincides with the northern limit of the forests. 

 On the southwest, its limits closely coincide with those of the 

 forests. He further emphasizes the distinction between bogs 

 and swamps. Bogs have been referred to as undrained swamps, 

 while swamps proper, in low ground and along stream courses, 

 are drained to a greater or less extent. Transeau, after elim- 



* This paper is intended primarily to give to teachers of botany a connected account 

 of what has been done in Amercia and in Europe in the investigation of peat bogs and it 

 incorporates the results of the author's observations of the bogs on the Pocono mountain 



plateau. 



t Transeau, E. N. On the Geographic Distribution and Ecological Relations of the 

 Bog Plant Societies of North America. Bot. Gaz., XXXVI : 401, 1903. 



