Vermont Shrubs and Woody Vines 



77 



than is any other plant or shrub as a means of preventing the 

 banks of streams from washing away. If nature did not plant 

 it, the land owners would probably have to provide some sub- 

 stitute as a soil binder. 



SMOOTH ALDER. 



(A. serrulata 



Alnus riigosa (Du Roi) Spreng. 

 Willd.) 



The smooth alder is the common species from Massa- 

 chusetts southward and naturally is more common in southern 

 Vermont than northward. In general 

 character and habit it is almost like the 

 preceding. Tn well-marked forms it is 

 easy to distinguish the two by the leaves. 

 Tt should be noted, however, that an in- 

 termediate form often occurring along 

 the shores of Lake Champlain puzzles 

 the student. The leaf of this form 

 has the shape of the hoary and the 

 color of the smooth alder. It is 

 listed as a hybrid in the "Flora of 

 Vermont" ; but whether or not this 

 is the true explanation must be deter- 

 mined by further study. 



Smooth Alder, X 



THE GRKEN AT.DERS 



There are two rarer northern species easily distinguishable 

 from the preceding by their smaller rounder leaves which are dis- 

 tinctly glutinous especially on the under side. It is also an in- 

 teresting fact that the fruit of these green alders seems free 

 from the gall fungus. The typical green alder {A. crispa (Ait.) 

 Pursh., A. viridis DC.) is found only on the higher mountain 

 summits. It is a small shrub of from two to six feet. The 

 larger form of lower altitudes which may rival the common 

 alder in size has recently been described as a distinct species 

 (A. mollis Fernald). It is distinguished from the mountain 

 species by more pubescent shoots and lower leaf surfaces. 



