Floristic Inventories of U.S. Bryophytes

Floristic Inventories of U.S. Bryophytes
		by *Alan Whittemore* Missouri Botanical Garden *Bruce Allen* Missouri Botanical Garden, St. Louis
Few floristic inventories of bryophytes have been made in the United States, primarily because of lack of trained personnel. The publication of modern manuals for the eastern United States for mosses (Crum and Anderson 1981) and liverworts and hornworts (Schuster 1966-92) has improved the situation. The paucity of manuals in the western United States is especially critical because of the uniqueness of the western North American flora. Eighty percent of the genera of bryophytes known to be endemic to temperate North America are confined to the area west of the 110th meridian (approximately the Rocky Mountains and west), but very few bryologists work there (Schofield 1980; Schuster 1984).
Mosses

The moss Leucolepis acanthoneuron. Courtesy D. Kearns, Missouri Botanical Garden

Mosses are the best known of the three bryophyte groups and have the most species: 1,320 species in 312 genera (Anderson et al. 1990). The only manual of mosses that treats all of North America north of Mexico is by A.J. Grout (1928-40), but is now outdated. Although this flora is unreliable for the mosses in the 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 Redfearn [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checklists of mosses for nearly every U.S. state (Pursell 1982), although many were published 30-40 years ago and are outdated.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 northern 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 published 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 considerably 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, which 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 continues 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 1985). 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 considered well-inventoried for liverworts or hornworts. The eastern half of the country is much better known than the West. The preparation of Schuster's manual of the liverworts and hornworts 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.

The liverwort Asterella echinella. Courtesy D. Kearns, Missouri Botanical Garden
Our knowledge of the liverwort and hornwort 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 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 hornwort floras in any meaningful way. Recent studies, though, describe several new taxa and some range extensions. For instance, Mannia fragrans, 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) revision of the xerophytic liverwort genus Plagiochasma increased the number of species known from the United States from three to five (adding two widespread Mexican species from Texas and Arizona). Numerous additions to the flora can be expected from this part of the country if intensive fieldwork is conducted.
Study of these plants has been handicapped by the lack 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 identification aids of any kind published for any area west of the 110th meridian, with the single exception of the brief checklist of the liverworts and hornworts 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 reliably 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 taxa continue to be found (for example, Pellia megalospora Schust. was not described until 1981). Further collection and study will surely provide many more range extensions. Likewise, the very distinctive endemic genus Schofieldia Godfrey was not described from western Washington until 1976, even though it is without close relatives and is rather common in subalpine sites from northwestern Washington north through the central part of the Alaska panhandle.
		For further information: Alan Whittemore Missouri Botanical Garden PO Box 299 St. Louis, MO 63166

References
Anderson, L.E., H.A. Crum, and W.R. Buck. 1990. List of mosses of North America north of Mexico. Bryologist 93:448-499. Bischler, H. 1979. Plagiochasma Lehm. et Lindenb. IV. Les taxa americains. Revue Bryologique et Lichenologique 45:255-334. 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. Flowers, S. 1973. Mosses: Utah and the West. Brigham Young University Press, Provo, UT. 567 pp. Grout, A.J. 1928-40. Moss flora 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 hornworts 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.	Merrill, G.S. 1993. Ozobryum ogalalense (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 eastern United States. Beihefte zur Nova Hedwigia 71:451-454. Redfearn, P.L., 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 bryology. Vol. 1. Hattori Botanical Laboratory, Nichinan, Japan. Sharp, A.J., H. Crum, and P.M. Eckel, eds. 1994. The moss flora of Mexico. Memoirs of the New York Botanical Garden 69. 1113 pp.

References

Anderson, L.E., H.A. Crum, and W.R. Buck. 1990. List of mosses of North America north of Mexico. Bryologist 93:448-499.

Bischler, H. 1979. Plagiochasma Lehm. et Lindenb. IV. Les taxa americains. Revue Bryologique et Lichenologique 45:255-334.

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.

Flowers, S. 1973. Mosses: Utah and the West. Brigham Young University Press, Provo, UT. 567 pp.

Grout, A.J. 1928-40. Moss flora 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 hornworts 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.

Merrill, G.S. 1993. Ozobryum ogalalense (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 eastern United States. Beihefte zur Nova Hedwigia 71:451-454.

Redfearn, P.L., 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 bryology. Vol. 1. Hattori Botanical Laboratory, Nichinan, Japan.

Sharp, A.J., H. Crum, and P.M. Eckel, eds. 1994. The moss flora of Mexico. Memoirs of the New York Botanical Garden 69. 1113 pp.

Floristic Inventories of U.S. Bryophytes

Mosses

Liverworts and Hornworts