30 FORESTRY MANUAL. 



mingling different kinds, each of which may draw different ingredients 

 from the soil, or extend their roots into the earth at different depths." 



" The ash," says C. W. Johnson, " and more particularly the locust, are 

 very obnoxious to most trees. Then again, the grouping together of certain 

 trees is particularly grateful to them all. Thus, the larch is a very good 

 neighbor ; the Scotch fir, the birch, and the Spanish chestnut grow very lux- 

 uriantly together ; the oak, the elm, the hazel, and the hornbeam, are very 

 good neighbors." 



In various places in the United States where men of mind and scientific 

 skill have directed in planting groves, for ornament or utility, they have in- 

 variably followed the teachings of nature, and intermixed very liberally the 

 various species of parent growth. In laying out the grounds of the Illi- 

 nois Industrial University, all the science and experience of the age was 

 brought into requisition to start a grove on the college grounds. Twenty acres 

 were set apart for an experimental forest tree plantation, in the grounds of 

 the university, and planted with Green ash, "White ash, catalpa, chestnut, 

 White elm, European larch, "White maple, Osage orange, Austrian pine, 

 Scotch pine, White walnut, "White pine, Norway spruce, and Sugar maple. 



The writer has noticed particularly the effect of isolation on the Lom- 

 bardy poplar (Populus dilitata.) It is a tree of rapid growth and is pe- 

 culiarly adapted to be used as shade trees along public and private high- 

 ways. But when thus planted it soon begins to fail and die at the top, and 

 soon becomes unsightly. But when it is mixed with other rapidly growing 

 trees, which keep pace with it, its health and greenness are longer perpetua- 

 ted. 



There is a slight disposition among fruit-growers to believe that if pine 

 trees are mixed through an orchard it will have a beneficial influence in 

 driving away the moth of many of the destructive insects which prey upon 

 apples and apple trees. It is supposed to be the strong effluvia issuing from 

 the turpentine of the pine. And others contend that the pine (all its varie- 

 ties; throws off in the grove, constantly in cold weather, a large amount of 

 warmth or caloric, which has a favorable influence on surrounding trees 

 during our boreal winters. In fact, it is contended by some scientific men 

 that all live trees have this influence, besides the protection which they im- 

 part as wind-breaks. And besides these benefits, some medical writers 

 claim that the influence of the turpentine in pine groves is highly beneficial 

 to the health of the human race, as well as to animals which dwell in well 

 ventilated pine groves. 



Nearly all the groves in Iowa, unfortunately, have a wearisome sameness. 

 They are either all cottonwood, Soft maple, or willow, with an occasional 

 highly redeeming exception in cases of walnut, oak, ash, etc. It is sincerely 

 to be hoped that more wisdom will be exercised in the future, and that the 

 lessons of the Great Teacher will be heeded in having groves of the greatest 

 possible number of acceptable varieties. 



These things are worthy of further demonstration by experiment, espe- 

 cially as it will cost nothing, but will add largely to the beauty and utility 

 of our groves. 



