40 



CIRCULAR 912, U. S. DEPARTMENT OF AGRICULTURE 



in the area for hedge or ornamental purposes. It was tested as an 

 ornamental at the Mandan station since 1916. The species suffered 

 winter injury during the winter of 1949-50 only. It does not sucker 

 under cultivation as do some other lilac species. The data indicate 

 it to be very suitable either as a windbreak shrub or as an ornamental — 

 in either group or trimmed-hedge form. 



Thuja occidentalis. — This species has been planted to a very limited 

 extent in the area. Some winter injury occurred each year, and losses 

 were very heavj^ during the severe drought years. The species is not 

 recommended for dry-land planting but is fairly satisfactory for orna- 

 mental purposes under irrigation. 



Tilia americana. — This species is native to the eastern edge of the 

 area and has been planted in some other parts of the northern Great 

 Plains as an ornamental. The trees in the test block suffered winter 

 injury each year. This resulted in a many-stemmed, shrubby type 

 of growth (fig. 10). Trees planted nearby under irrigation escaped 

 winter injury and developed a tree form of growth. The species is 

 highly recommended for planting under irrigation. 



Tilia europaea. — This species was tested only at the Mandan 

 station. The heavy winter killing and losses in stand which took 

 place during the severe drought years prevent the species from being 

 recommended for dry-land planting. It may possibly be satisfactory 

 for planting under irrigation. 



TJlmus americana. — This species is native to much of the area. It 

 grows in bottoms and other favorable moisture sites. The trees have 



/ 



Figure 10. — As the result of killing back each year, these trees of Tilia americana 

 growing under dry-land conditions developed multiple stems and a shrubby 

 type of growth. Under irrigation, for which it is highly recommended, the 

 species develops a tree form of growth. 



