FLOWERING PLANTS AND FERNS OF ARIZONA 3 



Laboratory, Tucson, Ariz.; Soil Conservation Service, United States 

 Department of Agriculture, Tucson, Ariz.; National Park Service, 

 United States Department of Interior, Grand Canyon, Ariz.: Cali- 

 fornia Academy of Sciences; University of California; Stanford Uni- 

 versity; Pomona College. 



C. V. Morton, of the Smithsonian Institution, has kindly reviewed 

 the manuscript and has contributed many helpful suggestions. 

 Finally, to Mrs. Rose E. Collom, Payson, Ariz., the writers are in- 

 debted for the privilege of using her manuscript notes on the habitat, 

 time of flowering, and economic uses of Arizona plants. 



PLAN OF THE WORK 



Keys are provided to the families, the genera of each family, and 

 the species of each genus. These are for the most part artificial. 

 Each pair of contrasting paragraphs in a key has the same indention 

 and the same introductory number (at the left) and this number is 

 not again repeated in the same key. Each paragraph ends (at the 

 right) with the name of a family, genus, or species, or else with a 

 number in parentheses, the latter indicating the pair of paragraphs 

 next to be referred to. Thus, if the characterization in the first 

 paragraph numbered 1 does not apply to the plant in hand, the user 

 of the key goes on to the second paragraph numbered 1. If this ends 

 in a number in parentheses, for example (4), the two paragraphs 

 numbered 4 are to be referred to next, and so on, until a paragraph 

 ending in a name and corresponding to the plant in hand is reached. 

 The sequence of families, genera, or species in the keys usually does 

 not correspond to their sequence in the text, but the number preceding 

 the name of the family, genus, or species in the key indicates its posi- 

 tion in the text. Thus, in the key to the families of seed-producing 

 plants (Spermatophyta) "5. Naiadaceae" stands third in the key, but 

 is the fifth family in the text. 



Brief descriptions are given of each family and genus; these, as 

 well as the characterizations in the keys, being worded, in the main, 

 so as to apply only to forms occurring in Arizona. Limitation of 

 space has made it impracticable to give descriptions of the species. 

 but the characterizations in the keys to species are usually ample, 

 and in many cases additional characters are mentioned under the 

 species in question. 



Lnder each species are given the geographical and altitudinal 

 range within the State, usually also the habitat and time of flowering, 

 and the general geographical distribution of the species. Type speci- 

 mens are cited, with few exceptions, only if the type was collected 

 in Arizona. Synonymy is limited, in the main, to (1) the name- 

 bringing synonym, (2) synonyms based on Arizona types, and (3) 

 names used in works often consulted in identifying Arizona plants, 

 such as YVooton and Standley, Flora of New Mexico. 1 Many species 

 included in this flora are not known definitely to occur in the State 

 but have been collected so near its borders as to make their occurrence 

 in Arizona highly probable. Such species are indicated by an asterisk 

 preceding the name. 



References are given, under many of the genera, to recently pub- 



1 Wooton, E.O.,andSTA\DLEv, P.C. flora of new mexico. Contrib. V. S.Natl. Herbarium 19: 1-794. 



1915- 



