74 ECOLOGY, PLANT GEOGRAPHY [BoT. Absts., Vol. X, 



11, May 17, and June 15 specimens detached from the mat and exposed to rain revived within 

 12-24 hours. On October 30 a specimen exposed to a warm mist revived sufficiently in 12 hours 

 to show that it was still alive, and in 12 hours more all the fronds were expanded. On March 8, 

 after more than 14 months without water, 2 fronds were still able to expand, after which the 

 plant did not revive. — J. C. Nelson. 



464. BoxNiER, G. Nouvelles observations sur les cultures experimentales a diverses 

 altitudes et cultures par semis. [New observations on experimental cultures at various altitudes 

 and seed cultures.] Rev. Gen. Bot. 32:305-320. 2 pi. ,4- fig. 1920. — An account is given of the 

 effects of climate upon perennial lowland plants cultivated for more than 30 years at altitudes 

 from 700 to 2400 m. in the Alps and Pyrenees. To eliminate the effect of initial variations 

 fully developed plants were divided into a number of parts, and these were transplanted to 

 various altitudes. The following are some of the conclusions reached: In general, all low- 

 land plants belonging to species naturally able to tolerate the differences in altitude develop 

 well under alpine conditions. Alpine species from other parts of the world grow well in anal- 

 ogous situations in the Alps and Pyrenees. At the end of 30 years in high altitudes nearly 

 all lowland plants have assumed the habit and anatomical structure identical with that of 

 plants of the same species already growing at these altitudes. Complete adaptation of this 

 sort is accomplished in 8 to 10 years by some species, whereas others require more than 25 

 years; 58 species which have undergone such changes are listed. — Several alpine plants (17 

 listed) have become so modified by the alpine climate that they are indistinguishable from 

 forms previously described as distinct species. For example, Helianthus vulgare Gaertn. 

 after 30 years at 2400 m. has assumed all the characters of H. grandifiorum DC. — All species of 

 extensive altitudinal range have an optimum altitude for their development. With increasing 

 altitude the leaves become greener and the flowers more highly colored up to a certain level; 

 beyond this level the colors become less intense, though some adaptive characters continue to 

 become more accentuated. Some changes appearing at once after transplantation disappear 

 in a few years; conclusions are valid only if based on observations extending over many 

 years. — Plants belonging to tj'^pical alpine species rapidly lose some of their alpine characters 

 or even perish when transferred to too low altitudes. The same is true of lowland species 

 grown at high altitudes and then returned to the plains. Some annual lowland species be- 

 come biennial or perennial at high altitudes ; the perennial habit represents one of the principal 

 alpine adaptations. — By a number of experiments with seeds germinated at low and high 

 altitudes it is shown that the seedling stages also show striking adaptations to alpine con- 

 ditions. The most conspicuous changes are the dwarfing of all parts and the alteration in the 

 shape and vesture of the leaves. — L. W . Sharp. 



465. Brewster, A. A. Pollination of Persoonia lanceolatus by the bee, Halictus. Austra- 

 lian Nat. 4: 157-158. 1920. 



466. Hamilton, A. A. Reproduction of plants from leaves. Australian Nat. 4: 149-150. 

 1920. 



VEGETATION 



467. Bbws, J. W. Plant succession and plant distribution in South Africa. Ann. Botany 

 34: 287-297. 1920. — The operation of Willis' "age and area" law is profoundly modified under 

 conditions of extreme climatic variation such as obtain in South Africa. The author attempts 

 to account for certain phases of plant distribution within the range under consideration by 

 the application of successional principles. lie finds that "species with a wide distribution 

 are usually found in an early stage of the plant succession." He regards this as an "eco- 

 logical amplification" of Willis' law applicable in regions characterized by great variations in 

 climate. It is pointed out that certain pioneer species are not widely distributed due to the 

 fact, in some cases at least, that their spread is prevented by the presence of more stable plant 

 communities. Furthermore, there are certain large classes of species having a restricted 

 distribution that "belong of necessity to climax or sub-climax stages of succession." — P. D. 

 Strausbaugh. 



