254 Floristik, Geographie, Systematik etc. 



Fern. & St. John), B. hyperborea cathancensis, and B. hyperborea 

 gaspensis. ___ Trelease. 



Fernald, M. L. and K. M. Wiegand. Some ne w species and 

 varieties of Poa from eastern North America. (Rhodora. 

 XX. p. 122—127. July 1918.) 



Poa saltuensis and its variety microlepis, and P. paludigena. 



Trelease. 



Ferris. R. S., Taxonomy and distributiou of Adenostegia. 

 (Bull. Torrey Bot. Club. XLV. p. 399-423. p. 10-12. Oct. 1918.) 

 Contains as new: Adenostegia Hanseni, A. parviflora, A. litto- 

 valis, A. Hellen, and A. palmata. Trelease. 



Gleason, H. A., The structure and development of the 

 plant association. (Bull. Torrey Bot. Club. XLIV. p. 463—481. 

 1917.) 



In these pages the author offers a series of general principles 

 in explanation of the usual phenomena of Vegetation, based chiefly 

 on observations of the writer in his own field work. They are 

 summarized as follows: 



All phenomena of Vegetation, i. e., of numbers of individuals, 

 depend upon the phenomena of the individual plant. 



The plant population of any area is determined by environ- 

 mental selection of immigrants from the surrounding population. 



Because of similarity of environmental selection and of available 

 sources of Immigration, areas of uniform Vegetation are developed, 

 known as plant associations. 



Effective changes in the environment or in the surrounding 

 population may lead to significant changes in the Vegetation of an 

 area. If these changes involve the establishment upon it of a new 

 association, the phenomenon is known as succession. Jongmans. 



Griffiths, D., New and old species of Opuntia. (Bull. Torrey 

 Bot. Club. XL VI. p. 195-206. pl. 9 10. June 1919.) 



Contains as new: Opuntia ejfulgia, O. cyanea, 0. diversispina, 

 O. hispanica, O. chata, 0. Maideni, O. obovata, and O. amarüla. 



Trelease. 



Griggs, R. F., Scientific results of the Katmai expedi- 

 tions ofthe National Geographie Society. 1. The reco- 

 very of Vegetation at Kodiak. (Ohio Journ. Sei. XIX. p. 

 1_57. With 32 illustrations. Nov. 1918.) 



Kodiak island was covered about a foot deep by the fall of 

 ash from the Katmai Volcano whose eruption oecurred on June 

 6, 1912. The effect of this was to give the island the appearance 

 of a pine barren, devoid of Vegetation except for the trees and 

 bushes which stuck through the ash uninjured. It still had this 

 appearance a year later in June 1913. In June 1915, however, it 

 was found that there had been a remarkable recovery of Vegeta- 

 tion, the grasses and other herbaeeous plants growing even more 



