E. V. Wulff —X— Historical Plant Geography 



The chapter on "Types of Areas" (V) could be illustrated more extensively from 

 American Uterature than Wulff has done. Maps prepared by M. L. Fernald and pub- 

 lished in various papers by him yield a wealth of material in this connection. The following 

 are references to a few of them: "Persistence of Plants in Unglaciated Areas of Boreal 

 America" (Mem. Gray Herb. 2, 1925); "The Antiquity and Dispersal of Vascular Plants" 

 (Quart. Rev. Biol, i: 212-45, 1926); "Some Relations of the Floras of the Northern Hemi- 

 sphere" (Proc. Int. Cong. PI. Sci. 2: 1487-1507, 1929); "Specific Segregations and Identi- 

 ties in Some Floras of Eastern North America and the Old World" (Rhodora 33: 25-63, 

 1931); "Recent Discoveries in the Newfoundland Flora" (Contr. Gray Herb. loi, 1933); 

 "A Century of Additions to the Flora of Virginia" (Contr. Gray Herb. 133, 1940). The 

 perplexing problem of species with ranges divided between North and South America has 

 been discussed recently by G. E. Du Rietz in "Problems of Bipolar Distribution" (Acta 

 Phytogeog. Suecica 13: 215-82, 1940). Students will find useful data on the marginal 

 phenomena of plant ranges, treated briefly by Wulff on p. 67, in papers by R. F. Griggs 

 on his investigations of timberlines: "The Edge of the Forest in Alaska" (Ecology 15: 

 80-96, 1934); "Timberlines in the Northern Rocky Mountains " (Ecology 19; 548-64, 1938); 

 "Indications as to Climatic Changes from the TimberHne of Mount Washington" (Science 

 9S: 515-19, 1942). 



Around the general subject of plant migrations and their causes there has grown an 

 imposing literature, both European and American. Students in the Americas will welcome 

 Wulff's resume of the European material, but will no doubt wish that circumstances had 

 permitted him to correlate it more fully with recent American work. The whole matter 

 has been greatly enlarged and complicated in recent years by the insertion of genetical 

 interpretations of plant behavior. It will be impossible to do more than cite a few of the 

 American papers which touch the problem. 



Hult^n's paper on an "Outline of the History of Arctic and Boreal Biota During the 

 Quartemary Period" (Stockholm, 1937) greatly extended many of the ideas already ex- 

 pressed by Fernald on Glacial and post-Glacial dispersal (see above, "Persistence, etc."). 

 The controversial issues of the "nunatak hypothesis" raised by Fernald have engendered 

 considerable stimulating discussion, much of which is summarized in papers by Frere 

 Marie- ViCTORiN, " Phy togeographical Problems of Eastern Canada" (Am. Midland Nat. 

 19: 489-558, 1935); V. C. Wynne-Edwards, "Isolated Arctic-alpine Floras in Eastern 

 North America: a Discussion of Their Glacial and Recent History" (Trans. Roy. Soc. 

 Can. III. 31(5): 1-26, 1937) and "Some Factors in the Isolation of Rare Alpine Plants" 

 (Trans. Roy. Soc. Can. III. 33(5): 35-42, 1939; R. F. Griggs, "The Ecology of Rare 

 Plants" (Bull. Torr. Bot. Club 67: 575-94, 1940); and by H. M. Raup, "Botanical Prob- 

 lems in Boreal America" (Bot. Rev. 7: 147-248, 1941). 



Notable advances in our knowledge of the origin and development of the great deciduous 

 forest complex of eastern America have been made in recent years by a number of students. 

 A paper by H. A. Gleason in 1923 on "The Vegetational History of the Middle West" 

 (Ann. Ass. Am. Geogr. 12: 39-85) has been followed, in the more purely floristic field, by 

 Fernald's "Specific Segregations and Identities, etc." (see above), E. L. Core's "Plant 

 Migrations and Vegetational History of the Southern Appalachian Region" (Lilloa 3: 5-29, 

 1938), E. Lucy Braun's papers on the "Afiinities of the Flora of the lUinoian Till Plain 

 of Southwestern Ohio" (Rhodora 37: 349-61, 1935) and "Some Relationships of the Flora 

 of the Cumberland Plateau and Cumberland Mountains in Kentucky" (Rhodora 39: 

 193-208, 1937); and by S. A. Cain's "Certain Floristic Affinities of the Trees and Shrubs 

 of the Great Smoky Mountains and Vicinity" (Butler Univ. Bot. Stud, i: 129-150, 1930). 

 Vegetational phases of the problem have been dealt with by Miss Braun in a series of 

 papers on the flora of southern Ohio and Kentucky: "Glacial and post-Glacial Migrations 

 Indicated by ReUc Colonies of Southern Ohio" (Ecology 9: 284-302, 1928); "The Un- 

 differentiated Deciduous Forest Climax and the Association Segregate" (Ecology 16: 

 514-19, 1935); "The Differentiation of the Deciduous Forest of Eastern United States" 

 (Ohio Jour. Sci. 41: 235-41, 1941); "The Forests of the Cumberland Mountains" (Ecol. 

 Monogr. 12: 415-47, 1942). The recent status of the eastern prairie-forest boundary prob- 

 lem was summarized in 1935 by E. N. Transeau in "The Prairie Peninsula" (Ecology 

 16: 423-37). 



Some recent papers on the interior plains of the continent are by Clements and 

 Chaney on "Environment and Life in the Great Plains" (Carnegie Inst. Wash. Suppl. 

 Publ. 24: 1-54, 1937); Forrest Shreve on "The Desert Vegetation of North America" 



