200 



I'liinLs — Our Livuii^ Rcsourctw 



For further information: 



Alan Whittemore 



Missouri Botanical Garden 



PO Bo\ 249 



St. Louis. MO 63166 



Te.xas and Arizona). Numerous additions to the 

 flora can be e.xpected from this part of the coun- 

 try if intensive fieldwork is conducted. 



Study of these plants has been handicapped 

 by the \iick of identification manuals over much 

 of the continent. The completion of Schuster's 

 manual (1966-92) has improved the situation in 

 eastern North America, but there is still almost 

 no usable literature from the western half of the 

 country. Since the first half of the century, there 

 have been no floristic treatments with identifi- 

 cation aids of any kind published for any area 

 west of the 1 1 0th meridian, with the single 

 exception of the brief checklist of the liverworts 

 and homworts of Olympic National Park by 

 Hong et al. (1989). In the whole of this large 

 area, which makes up more than half of the 

 country, specimens can only be identified reli- 

 ably by specialists with access to rare and often 

 outdated literature. Even in the well-studied 

 extreme Northeast (i.e.. New England and New 

 York), new ta.xa continue to be found (for exam- 

 ple. Pelliii nu'galosponi Schust. was not 

 described until 1981). Further collection and 

 study will surely provide many more range 

 extensions. Likewise, the very distinctive 

 endemic genus SchoficUlia Godfrey was not 

 described from western Washington until 1976. 

 even though it is without close relatives and is 

 rather common in subalpine sites from north- 

 western Washington north through the central 

 part of the Alaska panhandle. 



References 



Anderson. L.E.. H.A. Cruni. and W.R. Buck. 1990. List of 

 mosses of North .America north of Mexico. Bryologist 

 93:448-499. 



Bischler. H. 1979. Plaaiochiisniii Lehm. et Lindenb. IV. Les 



ta.xa americains. Revue Bryologique et Lichenologique 



4.S:2.'i5-334. 

 Crum. H. 1983. Mosses of the Great Lakes forest. 3rd ed. 



University of Michigan, Ann Arbor. 417 pp. 

 Crum. H.. and L.E. Anderson. 1981. Mosses of eastern 



North America. 2 vols. Columbia University Press. 

 Flov\'ers. S. 1973. Mosses: Utah and the West. Brigham 



Young University Press. Provo. UT. 567 pp. 

 Grout. A.J. 1928-40. Moss tlora of North America. 3 vols. 



.Self-published, New Fane. VT. 

 Hong. W.S.. K. Flander. D. Stockton, and D. Trexler. 1989. 



An annotated checklist of the liverworts and homworts of 



Olympic National Park. Washington. Evansia 6:33-52. 

 Lawton. E. 1971. Moss flora of the Pacific Northwest. 



Hattori Botanical Laboratory. Nichinan. Japan. 362 pp. 

 Memll. G.S. 1993. Ozobiyiim 0!;tiUileitse (Pottiaceae). a 



new genus and species from the American Great Plains. 



Novon 2:255-258. 

 Mogensen. G.S. 1985. Illustrated moss flora of Arctic North 



America and Greenland. Bioscience 17:1-8. 

 Pursell. R.A. 1982. A synopsis of moss floristics in the east- 

 ern United States. Beihefte /,ur Nova Hedwigia 



7 1 :45 1 -454. 

 Redfeam. PL.. Jr. 1983. Mosses of the Interior Highlands of 



North America. Revision Missouri Botanical Garden. St. 



Louis. 104 pp. 

 Schofield. W.B. 1980. Phytogeography of the mosses of 



North America (north of Mexico). Pages 131-170 in R.J. 



Taylor and A.E. Leviton. eds. The Mosses of North 



America Symposium. Pacific Division. American 



Association for the Advancement of Science. San 



Francisco. 

 Schuster. R.M. 1966-92. The Hepaticae and Anthocerotae 



of North America, east of the hundredth meridian. Vols. 



1-4. Columbia University Press. New York. Vols. 5-6, 



The Field Museum. Chicago. 

 Schuster, R.M. 1984. Phytogeography of the Bryophyta. 



Pages 463-626 in R.M. Schuster, ed. New manual of bry- 

 ology. Vol. I. Hattori Botanical Laboratory. Nichinan. 



Japan. 

 Sharp. A.J.. H. Crtim. and PM. Eckel, eds. 1994. The moss 



flora of Mexico. Memoirs of the New York Botanical 



Garden 69. 1113 pp. 



Vascular 

 Plants of the 

 United States 



by 



Nancy Moriii 



Missouri Botanical Garden 



Information tin the plants of the United States 

 can be found in floras, monographs, and var- 

 ious lists and reports. Herbarium collections 

 provide an invaluable record of past and current 

 distributions of U.S. plants and form the basis 

 for published accounts of the plants such as flo- 

 ras and checklists. Properly understanding and 

 managing U.S. plant resources depend on hav- 

 ing physical samples that document the charac- 

 teristics and distributions of plants and on the 

 scientific studies of the relationships, character- 

 istics, distributions, and physical requirements 

 of the plants. Although such documentation 

 exists for some areas of the country, many areas 

 are still poorly known, and authoritative refer- 

 ences are still lacking for some. 



About 17.000 species of vascular plants (i.e., 

 flowering plants, gymnospemis, and ferns) 

 occur in the contiguous United States and 

 Alaska (Flora of North America Editorial 

 Committee 1993): Hawaii is home to more than 

 1,800 species of flowering plants (Wagner et al. 



1990). few of which are found on the North 

 American mainland. Trees have been most com- 

 pletely documented, followed by shrubs and 

 showy herbaceous plants. Known distributions 

 of rare plants are generally available in comput- 

 erized data bases, often maintained by state 

 Natural Heritage Programs. Nationwide data- 

 base files for rare plants are maintained by The 

 Nature Conservancy. 



Non-natives and inconspicuous natives are 

 often overlooked by plant collectors and thus 

 are less well documented. In much of the conti- 

 nent, and especially in highly populated areas, 

 however, the native flora has been altered so 

 completely by humans that "native" or "natur- 

 al" vegetation is almost beyond conception. 

 Because of this, the historical portrait of plant 

 distribution that can be drawn based on herbar- 

 ium specimens is extremely valuable to under- 

 stand the pre-Columbian composition of our 

 tlora and the relation of plants to their environ- 

 ment. Modern collecting still brings many new 



