Figure 10. — Wood's rose plants have attractive 

 flowers and provide a protective soil covering. 



on sites where it was able to establish well. Blackcap 

 exhibited vegetative spread quite similar to that of 

 Wood's rose. None of the other species successfully 

 regenerated by seed or root propagation. 



Soil Stabilization 



As previously discussed, growth and natural spread 

 contribute to stabilization of soils on the cut banks. 

 Surface coverage exhibited by Wood's rose (fig. 4) 

 and the mat-forming bush penstemon (fig. 10) protect 

 the surface and hold the soil against water and wind. 

 These plants can grow on, survive on, and enhance the 

 appearance of very rocky sites (fig. 12). Root type and 

 depth are important for holding deeper layers (table 2). 

 Plants with rhizomes, such as Wood's rose, blackcap, 

 thimbleberry , and spirea, may function better in holding 

 soil than plants with other types of root systems. Wood's 

 rose and blackcap plants developed extensive rhizomes 

 on the study sites. This was not observed for 

 thimbleberry or spirea. Root systems for lovely and 

 bush penstemons were well developed and seemed to 

 hold soil well on these steep cut banks. Other species, 

 such as red-osier dogwood, redstem ceanothus, and 

 snowbrush, develop deep root systems and provide 

 good stabilization where plants grow well. 



Suitability Ratings 



Overall assessment of species suitability was based 

 on survival, growth, vigor, natural spreading, and soil 

 stabilization. Species were ranked according to these 

 factors (table 3). Wood's rose achieved the highest 

 ranking, with bush penstemon and lovely penstemon 

 second and third and red-osier dogwood fourth. Wood's 

 rose scored well in all categories, indicating good po- 

 tential for cut bank stabilization. Red-osier dogwood 

 achieved a high ranking because of its high survival 



Figure 11. — Bush penstemon plants grow on 

 rocky sites and spread by seed. New plants are 

 located in the ditch and to the side of the original 

 rows. Closeness of plants in the row demon- 

 strates plant expansion and new plants. A good 

 ground cover that is effective in stabilizing soils 

 is produced. 



Figure 12. — Appearance of this rocky road cut 

 is improved by flowering bush penstemon, 

 Wood's rose, and black chokecherry plants. 

 These plants have persisted for 9 years with 

 good growth. 



rates, but it did not show evidence of natural spreading. 

 Red-osier dogwood, though it performed surprisingly 

 well, cannot be assumed to be as well adapted to the 

 study sites as both penstemons. Both penstemons 



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