284 ECOLOGY [Bot. Absts. 



the natural undergrowth has been practically destroyed. — The canyons are the centers of 

 scenic interest; they are characterized by great diversity of plant life and the presence of 

 many rare species. A half dozen liverworts and twice as many species of ferns make up a 

 very interesting portion of the plant population. — The river bluffs present the opposite of 

 living conditions noted in the canyons. In the latter shade and moisture are prevalent 

 while in the former full exposure to sun and wind results in a habitat suited only to such plants 

 as are found in dry areas. However, certain plants found commonly in bogs and swamps 

 are present here, owing to the fact that absorption of water in these exposed situations is 

 no more difficult than it is under bog conditions. — The fertility of the bottom lands has made 

 them very desirable for agricultural purposes so that in large part the natural vegetation has 

 disappeared. Only on flood plain margins and on the river islands can an idea of the rich- 

 ness of this natural vegetation be obtained. — The author concludes with a brief account of 

 the history of the flora, and an analysis of the changes that are in progress at the present 

 time. — P. D. Strausbaugh. 



1953. De Vries, Hugo. The relative age of endemic species. Science 47: 629-630. June, 

 1918. — De Vries reasserts his belief in the validity of the age-and-area hypothesis of Willis, 

 concluding that "in every systematic group of plants the rule prevails that the most wide- 

 spread species are the oldest, whereas the others are younger, the smaller their area is." — P. 

 D. Strausbaugh. 



1954. Dorset, M. J. Adaptation in relation to hardiness. Minn. Hortic. 46: 465-469. 

 1 fig. 1918. — Certain data bearing on the relation of the maturation period to hardiness are 

 presented. There is an essential difference between a variety and a species in respect to 

 growth response as a result of adaptation to environment. The author says, "it would be 

 expected, however, that the same forces operating to produce differences in a species would 

 do the same in time with variations arising within a variety." — P. D. Strausbaugh. 



1955. Du Rietz, G. E. Th. C. E. Fries, and T. A. Tengwall. Vorschlag zur Nomen- 

 klatur der soziologischen Pflanzengeographie. [Nomenclature in sociological plant geography.] 

 Svensk. Bot. Tidskr. 12: 145-170. 1918. — A discussion of phytogeographical classification 

 including descriptions, examples and definitions of the terms used, such as formation, asso- 

 ciation, facies, aspect, etc. Emphasis is placed upon the need for a clearer and more unified 

 nomenclature in the literature dealing with phytogeographical classification. — P. D. Straus- 

 baugh . 



1956. Emig, W. H. The travertine deposits of the Arbuckle Mountains, Oklahoma, with 

 reference to the plant agencies concerned in their formation. Oklahoma Geol. Surv. Bull. 29. 

 76 p. 22 fig. 2 pi., 2 maps, 1 table. 1918. — The travertine forms several waterfalls in creeks 

 in the Arbuckle Mountains, in the semi-arid southwestern part of the state, and algae and 

 mosses have played an important part in its deposition. [See also Bot. Absts. 2, Entry 222.] 

 — Roland M. Harper. 



1957. Ferguson, William C. Plants in flower in the autumn of 1918 on Long Island, 

 N. Y. Torreya 19: 12-13. 1919.— The autumn of 1918 was warmer than any previously ob- 

 served in this vicinity. A list is given of 16 species in fresh bloom at Garden City, L. I., on 

 Oct. 28-30, 1918, and a second list of 50 species collected between Pine Lawn and Lake Ron- 

 konkoma on Nov. 1-2. — J. C. Nelson. 



1958. Gleason, Henry A. On the development of two plant associations of northern 

 Michigan. Plant World 21 : 151-158. June, 1918. — Describes successional stages in the cleared 

 maple-beech forests and in abandoned fields in same region. Tables show frequency indices 

 of all plants in quadrats studied at two and three year intervals. The principal species in 

 clearings are Acer pennsylvanicum , Sambucus racemosa and Rubus idaeus. The maples re- 

 quire five years to reestablish their dominance. The dominant plant in abandoned fields ia 

 Poa pratensis. — Forrest Shreve. 



