TREES AND SHRUBS FOR THE NORTHERN PLAINS 29 



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Figure 3. — Trees of Fraxinus mandshurica have a very erect form of growth and 

 have narrow crowns. These factors make the species desirable as an ornamental 

 if supplemental water is available. 



killed-back trees became suppressed. The species has an erect form 

 of growth and a narrow crown, which makes it desirable for ornamental 

 purposes if irrigation water is available. It is not suitable for dry-land 

 planting. 



Fraxinus pennsylvanica var. lanceolata. — This species is native to the 

 area and has been widely planted for windbreak and ornamental pur- 

 poses. The trees suffered heavy winter injury during the severe 

 drought years of 1934 and 1936 only. The species does not thrive in 

 shade; trees suppressed by shade frequently kill back. Weakened 

 trees are susceptible to borer infestation throughout much of the area. 

 This species is one of the best for windbreak purposes both under dry- 

 land conditions and under irrigation. 



Fraxinus sp. (P. I. 65866). — This species was tested at the Mandan 

 station only. The trees were killed back frequently and they showed 

 no promise of being suitable for dry-land planting in the area. 



Gleditsia sinensis. — This species was tested at the Mandan station 

 only. Severe winter injury occurred each year prior to 1947. It was 

 less severe afterward. Failure of the species to set terminal buds in 

 the fall makes its value for use in the area doubtful. 



Gleditsia triacanthos. — This species has been planted to a limited 

 extent throughout the area. Ordinarily, the trees are subject to killing 

 back during the winter months. However, a few were found which 

 have been entirely cold-hardy to date. The species will not be recom- 

 mended for general planting until favorable results are obtained in 

 further tests. 



Halimodendron halodendron. — This species was tested at the 

 Mandan station only. Winter injury was never severe. H. halodendron 



