136 PHYSICAL GEOGKAPHY. 



so few in number that they hardly deserve mention as varieties 

 of fuel. In the new natural growth of these trees the relative 

 abundance is somewhat changed, the black oak, hickory, and 

 black walnut increasing. The following named trees are 

 those which will probably be most used for cultivation. 

 They are given in the order of their estimated rapidity of 

 growth: Cottonwood, white maple, black walnut, oaks, 

 sugar maple, and hickory. 



The relative value of each of these kinds of wood for fuel 

 is estimated to be in the same order, cottonwood being the 

 poorest and hickory the best; or, in other words, the slower 

 the growth of the tree, the more valuable it is for fuel. But 

 taking into account the necessity that exists for immediate 

 supplies of fuel in many parts of Iowa, the cottonwood 

 becomes one of our most valuable trees because of its rapid 

 growth. As soon as it has performed this valuable pioneer 

 service, it should be laid aside to give place to more solid and 

 useful varieties. 



The most congenial habitat of the cottonwood is upon the 

 sandy alluvial soils of the river-valleys; but it grows with 

 astonishing rapidity upon all varieties of soil in the State, and 

 flourishes as well upon the prairies as in the valleys. 

 Instances are numerous of the growth of this tree from the 

 seed, or from a riding stick stuck into the prairie soil, to the 

 size of from twelve to fifteen inches in diameter, a foot above 

 the earth, within the space of ten or twelve years. So rapid is 

 its growth that those well acquainted with it estimate that ten 

 acres planted with the seeds or young shoots, will, at the end 

 of five years, supply a large family continually with all neces- 

 sary fuel. Indeed a large number of persons have practically 

 proved the correctness of these estimates. 



Cottonwood may be propagated either from the seed, 

 cuttings, or by transplanting the young trees. The seed, 

 which is very light, is sometimes scraped up from the sandy 

 surfaces along the streams where it has fallen from the trees, 

 the seed and sand mixed together and sown broadcast upon 

 ground prepared for it, as small grain is sown. Sometimes 



