MANUAL OF THE GRASSES OF THE UNITED STATES 



11 



The sequence of tribes and genera 

 in the manual with a few minor 

 changes, is that found in The Genera 

 of Grasses of the United States. 2 



NOMENCLATURE 



The cooperative study of botany- 

 depends for progress and success on 

 definiteness in the application of the 

 names of plants. Research workers 

 in all branches of botany must use 

 the names of plants in the same 

 sense, or serious misunderstandings 

 will result. One of the functions of 

 systematic botany is to determine 

 the correct names of plants. The 

 study of the application of plant 

 names is nomenclature. By common 

 consent of the botanists of the world 

 Latin has been accepted as the 

 language for technical plant names. 



Modern nomenclature commences 

 with the publication in 1753 of 

 Linnaeus' Species Plantarum in which 

 the binomial system of naming plants 

 was first proposed. During the nearly 

 200 years following that date many 

 thousands of plants have been de- 

 scribed. During this time there has 

 been a lack of uniformity in the use 

 of names, causing much confusion 

 and resulting in frequent changes. 

 The same species has been described 

 under different names at different 

 times, and the same name has been 

 given to different plants. This con- 

 fusion has been especially embarrass- 

 ing to the agriculturist, ranger, seeds- 

 man, pathologist, entomologist, and 

 to all others interested in plants but 

 not familiar with nomenclature and 

 the history of the names used. 



The difference in the Latin names 

 applied in different books to the same 

 kind of grass is due to several causes. 



(1) A species is described as new by one 

 author without knowing that the same spe- 

 cies had been previously described by an- 

 other author. The second name is known as 

 a synonym. 



(2) An author applies a new name to a 

 variant of a species already described. The 



2 Hitchcock, A. S. the genera of grasses of the 



UNITED STATES, WITH SPECIAL REFERENCE TO THE 



economic species. U.S. Dept. Agr. Bui. 772, 307 pp., 

 illus. 1920, revised 1936. 



author recognizes the variant as a distinct 

 species. Other botanists may consider it to be 

 only a variety of the older species or may 

 consider it as a variant not sufficiently dis- 

 tinct to be worthy of varietal rank. 



(3) Authors have different concepts of the 

 limits of genera. The genus Triticum was 

 described by Linnaeus. A later botanist 

 thought that many of the species of this 

 genus were different enough to constitute a 

 distinct genus, Agropyron, and transferred 

 quackgrass, first described as Triticum re- 

 pens to Agropyron, as A. repens. 



(4) Authors sometimes misidentify spe- 

 cies. Linnaeus described one of the cord- 

 grasses as Spartina cynosuroides. Later, 

 Michaux used the specific name for a differ- 

 ent species (Trachynotia cynosuroides, based 

 on S. cynosuroides L.) This error was cor- 

 rected and the species described by Michaux 

 was given a new name, S. michauxiana. 

 Later the loan of the type of Spartina pec- 

 tinata Link, poorly described many years 

 earlier, shows that that name is the valid 

 one for the species. 



It will be seen that the differences 

 in names are due in part to differences 

 of opinion as to the generic, specific, 

 or varietal distinctness of forms; in 

 part to lack of knowledge as to what 

 plants have been describedpreviously ; 

 and in part to errors of identification. 



All the preceding shows the need 

 of rules of nomenclature. To enable 

 users of this manual to coordinate 

 the names published to date a syn- 

 onymy has been appended in which 

 all the names published for grasses 

 in the United States have been ar- 

 ranged under the names here adopted, 

 that is, under the oldest valid name 

 for each species. In determining the 

 valid names of the species the Inter- 

 national Rules of Botanical Nomen- 

 clature have been followed. Under 

 these rules certain generic names are 

 conserved though they are not the 

 earliest. The names of genera of 

 grasses on the conserved list are as 

 follows: Chrysopogon, Tragus, Zoysia, 

 Setaria, Leersia, Ehrharta, Hierochloe, 

 Crypsis, Coleanthus, Corynephorus, 

 Cynodon, Ctenium, Buchloe, Diarrhe- 

 na, Lamarckia, Glyceria, Scolochloa. 



Certain other names of genera are 

 used for different reasons. Digitaria 

 antedates Syntherisma with which it 

 is synonymous. It was proposed at 

 the Cambridge International Botan- 



