270 ' Floristik etc. — Angewandte Botanik. 



Trelease, W., Plant materials ofdecorative gardening >|c 

 the Woody plants. (Urbana, Illinois, Published by the Author. 

 1917. Price $ 1.00.) 



A pocket manual of 204 pp., keying out 247 genera, 782 spe- 

 cies and 375 varieties, pertaining to 83 natural families. Intended 

 for the field Identification of the usual cultivated woody plants of 

 northern Europe and the northern United States. Two new 

 names have crept in: Carya ovata hirsuta and Broussonetia papyri- 

 fera contraria. Trelease. 



Wernham, H. F., Tropical American RnUaceae. IX. (Journ. 

 Bot. W 657. LV. p. 251-254. Sept. 1917.) 



Psychotria Aschersonianoides, P. flavivetiter, P. sutericalyx, P. 

 mineirensiSj P. articuUcymosa, P. fatniliarifoHaj P. halophiloides. 



E. M. Cotton. 



Willis, J. C, The Relative Age of Endemie species and 



other Controversial Points. (Ann. Bot. XXXI. p. 189-208. 



1917.) 



This paper is a reply to the criticisms of the author's hypothe- 



sis of „age and area" in plant distribution , made by H. W. Ridley 



(Endemism and the Mutation Theory. Ann. Bot. XXX. 1916. p. 551). 



In the present Willis pays special attention to the view maintained 



by Ridley and other botanists, that endemics are chiefly relics of 



an old flora. Owing to its controversial nature, it is scarcely pos- 



sible to summarise this paper, but it should be noted that, in 



addition to replies to criticism, it contains some fresh material bea- 



ring on the law of „age and area". Agnes Arber (Cambridge). 



Wilson, P., The Vegetation of Vieques Island. (Bull. N. Y. 

 Bot. Gard. VIII. p. 379—410. f. 1. June 9, 1917.) 

 Contains as new: Roystonea caribaea {Euterpia caribaea S^^reng.), 

 Byrsonima cuneata {Malpighia cuneata Turcz.), Ricinella Ricinella 

 Britt. [Adelia Ricinella L.), Charnaesyce Vahlii {Euphorbia Vahlii 

 Willd.), Icacorea guadalupensis Britt. {Ardisia guadalupensis Duch.), 

 and Tepion alatum Britt. {Verbesina alata L.). Trelease. 



Balls, W. L. and F. S. Holten. Analyses of agricul tural 

 yield. Part 2. The Sowingdate experimentwithEgyp- 

 tian cotton. (Phil. Trans. Roy. Soc. B. CCVI. p. 403-480. 1915.) 



Experiments have been made to enquire into the effects pro- 

 duced by sowing cotton at weekly intervals, from a month before 

 the conventional date up to a month after it. The results confirm 

 the native custom, which is against very early sowing; apparently 

 there is an Optimum sowing date, and sowings made before or 

 after this tend to produce poorer crops. A very füll description is 

 given of all the experimental methods and the special precautions 

 that had to be observed. 



Provided that the seed coat can absorb ample water, the limiting 

 factor of field germination is temperature, and the rate of germina- 

 tion increases with rise of temperature up to 30° C; temperatures 



