How to Use the Synonymy 



The synonymy lists all genera that were included in source 

 manuals or were accepted for the U.S. regions by the 

 Smithsonian Institution. The synonomy does not include all 

 accepted names, so do not use it unless you have first looked 

 in the list for the region you are concerned with. 



If you have checked the list covering the appropriate region 

 and have not found the name you were seeking, look it up 

 alphabetically by genus in the synonymy. Within the genus, 

 species are also listed alphabetically. When you look up the 

 species, you will find one of the following cases: 



"Accepted" will not appear to the far right, and one or more 

 synonyms will be listed after the species. Symbols between 

 the name you looked up and its synonym will explain the 

 relationship between the two names. If the synonym is part 

 of the same genus, you may use the family name and 

 number to look up the synonym (using the instructions to 

 volume 1 ) . 



If the synonym is in a different genus, you will need to look 

 up that genus in the Guide to Family Numbers (volume 1, 

 p. 7). For example, had you looked up Rhus radicans in 

 volume 1 to see if it were the accepted name for poison ivy, 

 you would not have found it. Then you would look up Rhus 

 radicans in the synonymy and find Toxicodendron radicans 

 listed as a synonym. Then you could look up Toxicodendron 

 in the Guide to Family Numbers and proceed as described 

 on page 1 of volume 1. 



If the name you are looking up is a subspecies or variety, a 

 synonym may not be listed. If one is not listed, check to see 

 if the species, listed above the subspecies or variety, has 

 "Accepted"' written in the right-hand column. If it does, the 

 species is the accepted name. For example, Abronia 

 angustifolia var. arizonica (p. 5) is not an accepted name and 

 has no synonym listed. However, the species A. angustifolia 

 is accepted, so that is the name you should use. 



Also, if a synonym is listed for a species, varieties and 

 subspecies under that species will take the synonym of the 

 species unless a separate synonym is shown for them. For 

 example, Acer grandentatum var. brachypterum (p. 7) has 

 no synonym listed. Acer grandentatum is not accepted, but a 

 synonym is listed. That synonym would also be used for 

 A. grandentatum var. brachypterum. Acer grandentatum var. 

 sinuosum, however, has a separate synonym listed, which 

 is the correct synonym. 



In rare instances, you may find one of two other possibilities. 

 If the plant is not listed, the name was not included in our 

 sources and the consultants did not consider it a valid name. 

 If the species is listed but no synonym is given, then it was 

 included in our sources, our consultants considered it 

 invalid for a United States plant, but they could not 

 determine the valid synonym. If you encounter either of 

 these possibilities and the plant is important on your site, 

 you probably should submit a herbarium specimen for 

 identification by a local or national authority. 



