Trees, native, naturalized, and cultivated Previous lists of forest trees of the United States.... Page This check list aims to compile the accepted scientific nam and current synonyms, approved common names and others use, and ranges of the native and naturalized trees of the Unite States of America (including Alaska). It is primarily a refe ence for foresters, botanists, students, and all others intereste in trees. One of its important objects is to encourage unifor usage of names for trees. The third in a series, this is th official standard for tree names in the Forest Service. There are four outstanding reasons for issuing a new chec list. First, the former standard for tree names in the Fores Service, Check List of Forest Trees of the United States b George B. Sudworth (44)1 issued in 1927, is out-of-print, anti quated, and moreover, chiefly under the obsolete "America Code" of nomenclature. Second, some changes in scientific name have been required to conform to the International Code o Botanical Nomenclature (14a), formerly the International Rule of Botanical Nomenclature (1, 4, 30) which incorporated certai desirable features of the "American Code" when the two wer consolidated in 1930. These rules were officially adopted by th United States Department of Agriculture on April 30, 1940, an were revised slightly in 1950. Third, the common names hav been revised by the Forest Service Tree and Range Plant Nam Committee. Finally, much additional information about the tree of the United States, their taxonomy or dendrology, has becom available through numerous investigations and researches by botanists and foresters during this 25-year interval. Critical field, herbarium, and experimental studies have resulte in taxonomic revisions of various genera of trees and bette understanding of the different kinds of trees and their relation ships. Botanical exploration of the country including even th most remote regions has been advanced greatly by numerou plant collectors and field workers, aided by improved automobil transportation. A few new species of local range and additiona varieties and natural hybrids have been named among the nativ trees. Likewise, many former varieties and some species hav been found upon further study not to be distinct and have bee reduced to synonymy. Range extensions northward of Mexica and tropical species along the southern boundary have bee recorded, and with the passing of time more introduced tree have escaped from cultivation and have become naturalized Tree individuals have been found among species previousl known only as shrubs. Many good State and local floras and publications on tree have contributed much valuable information on distribution, s that the ranges of individual tree species are now known mor accurately and in much greater detail. However, as much of th 1 Italic numbers in parentheses refer to Literature Cited, p. 24. |