Our L/i'/oi; Resources — Plants 



199 



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I ho moss lA-tii.(>Upt\ iiciinihoiu'uroii 



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midcontinent, it covers the mosses from the 

 eastern United States and the west coast regions 

 well. 



The eastern forest region is the strongest 

 area for moss floristics in the United States. The 

 United States east of the Mississippi is covered 

 well by Crum and Anderson's (1981) flora. 

 Most states there have recent checklists of 

 mosses. In addition, several regional floras 

 cover parts of more than one state (e.g.. Crum 

 [1983] for upper Michigan and nearby areas and 

 Redfeam [1983] for the Ozark region). 



The distribution of mosses in other parts of 

 the country is not as well known. There are 

 checklists of mosses for nearly every U.S. state 

 (Pursell 1982). although many were published 

 30-40 years ago and are outdated. The 

 Southeast has the fewest checklists; the north- 

 em parts of Mississippi. Alabama, and Georgia 

 and the southern parts of Arkansas are poorly 

 known. 



The Southwest is also one of the least known 

 U.S. areas. It has great diversity of habitats 

 including mountains, grasslands, and desert 

 habitats. Although checklists have been pub- 

 lished for all of the states and a flora has been 

 published for Utah (Flowers 1973). the mosses 

 of Nevada. Arizona. New Mexico, and parts of 

 Texas are probably still the least known in the 

 country. The recent publication of the moss 

 flora of Mexico (Sharp et al. 1994) will consid- 

 erably aid workers in this region, but much 

 basic floristic work needs to be done. 



Good state checklists exist for the Great 

 Plains and the Pacific Northwest, wh'ch has 

 checklists for the entire region as well as a 

 regional flora (Lawton 1971). The Great Plains 

 is reasonably well covered with checklists and 

 two regional floras for all of the midcontinent. 

 Moss diversity in this region is low, and many 

 of the mosses are members of the eastern moss 

 flora. But the mosses in this region have not 

 been extensively surveyed, and the area contin- 

 ues to yield surprises such as Ozobryum 

 ogalalense. a new genus (Merrill 1993). 



Alaska has a checklist and work has begun 

 on a synoptic flora that will cover the Arctic 



area (Mogensen 1983). Floristically. however, 

 the Arctic areas of Alaska are fundamentally 

 different from the rest of the United States. A 

 portion of flora can be named by using Arctic 

 European floras; otherwise, the flora can be 

 named only by specialists with access to the 

 scattered literature and a good herbarium. 



Liverworts and Hornworts 



No part of the United States can be consid- 

 ered well-inventoried for liverworts or hom- 

 worts. The eastern half of the country is much 

 better known than the West. The preparation of 

 Schuster's manual of the liverworts and horn- 

 worts of eastern North America (1966-92). 

 which resulted in the publication of several 

 dozen new species (mostly from the southern 

 Appalachians and Florida), has improved our 

 knowledge of these plants in the East. Many 

 taxonomic problems still need serious study, 

 however, and known ranges of distribution are 

 still incomplete. 



Our knowledge of the liverwort and hom- 

 wort floras in the western half of the country 

 has improved recently because of a series of 

 local checklists (mostly of national parks and 

 similar small floristic units) for the Pacific 

 Northwest. For large parts of the northwestern 

 United States, however, we still rely on a few 

 pioneering studies from 1890 to 1940. 



The liverwort Asterella echineUa. 



The most poorly known part of the country 

 is undoubtedly the interior Southwest (New 

 Mexico, Arizona, and surrounding regions). 

 Data from this area are so scanty and inadequate 

 that it is difficult to assess the regional liverwort 

 and honiwort floras in any meaningful way. 

 Recent studies, though, describe several new 

 taxa and some range extensions. For instance. 

 Mannia fragnms. which seems widespread in 

 the mountains of the western United States, was 

 not reported from any state west of Colorado 

 before 1987. Likewise. Bischler's (1979) revi- 

 sion of the xerophytic liverwort genus 

 Phigiochasma increased the number of species 

 known from the United States from three to five 

 (adding two widespread Mexican species from 



