COMPARATIVE WOOD ANATOMY OF SOME SHRUBS NATIVE TO 

 THE NORTHERN ROCKY MOUNTAINS 



Arlene Dale 

 INTRODUCTION 



Presented here is a key for identification of shrubby plants native to the Northern Rocky 

 Mountain area. This key supplements those already in existence that are based on plant organs, 

 such as flowers, leaves, fruits, and other macroscopic characters. In contrast, the characters 

 upon which this key is based are those of the wood, or technically, the xylem. Such a key would 

 be valuable to substantiate identifications made by means of the ordinary keys and to aid in the 

 identifications of plants when flowers , leaves , and fruits are not available . 



Fifty-five species, representing 35 genera (see page 3), have been incorporated in this 

 key. Xylem characters determined the arrangement of the species. Where certain characters 

 were held in common by all genera of a family, these species parallel their usual taxonomic 

 arrangement. Depending on characters present, identification is to a species, a genus, or a 

 group of genera. Further study will make possible more detailed identification. 



A review of the literature concerning wood anatomy indicates a change in emphasis has 

 occurred within the past 20 years --from a heavy reliance on quantitative data in distinguishing 

 among woods to the use of qualitative characters. This change has been caused by increased 

 understanding of the extent and causes of variations within a species. No longer is it assumed 

 that a single specimen accurately represents a species. To determine the range of variability 

 of all 55 species was beyond the scope of this study; the diversity of characters within each 

 species will be discovered only as this key is used. In this key, cell patterns - -created by the 

 ordered activity of the cambium --are employed extensively. 



METHODS AND MATERIALS 



FIELD COLLECTIONS 



Specimens were collected for over 60 species of shrubs from sites in western Montana 

 and northern Idaho.'" Several of these species were rejected from consideration because they 

 were represented by only one specimen; others were rejected because the specimens collected 

 were only 1 year old. While some species were represented by as many as five specimens, the 

 minimum number was two. 



Most of the collections and all of the identifications were made by Peter F. Stickney, 

 Associate Plant Ecologist, U.S. Forest Service, Intermountain Forest and Range Experiment 

 Station. Identifications were made by means of the following: Hitchcock, C. L. , A. Cronquist, 

 M. Ownbey, and J. W. Thompson. Vascular plants of the Pacific Northwest. Seattle: Univ. 

 Wash. Press. Part 2: Salicaceae to Saxifragaceae, 1964; Part 3: Saxifragaceae to Ericaceae, 

 614 pp. , 1961; Part 4: Ericaceae through Campanulaceae , 510 pp. , 1959; Part 5: Compositae, 

 314 pp. , 1955. 



