1890.] |. Origm of the Plane-Trees. 797 
ORIGIN OF THE PLANE-TREES. 
BY LESTER F. WARD. 
HE fourth number of Volume XI. of Engler’s Botanische 
Jahrbücher contains an elaborate article by Johann Jankó, 
entitled “ Abstammung der Platanen.” The writer treats the 
subject in the characteristic German fashion, approaching it in an 
exhaustive manner from every possible point of view; and his 
contribution throws much light upon this interesting type of 
plant life. He had thoroughly prepared himself by careful 
observations continued during a number of years, and by col- 
lections, made at different and critical seasons of the year, from all 
the species of Platanus growing wild or in cultivation in Europe. 
He had also carefully studied the fossil forms, apparently only 
from the published figures, and evinces a wide acquaintance with 
these as well. He makes a searching revision of the species, 
both living and fossil, reducing the former to three, with numer- 
ous varieties, and the latter to eight. 
The object of the paper, as indicated by its title, is to derive 
the living species from the fossil ones, and to show the line of 
descent of the former. The title is, nevertheless, misleading, 
since it would imply that the author was seeking the origin of 
the genus itself. So far is he from this that he rules out of the 
genus all the archaic forms occurring in the earlier formations, 
including P. nobilis of Newberry, and gives no intimation as to 
whether he regards them as ancestors of Platanus. 
The following is his disposition of the fossil species : 
With P. aceroides (Göpp.) Heer, he unites: P. aceroides cunei- 
folia Gaudin, P. cuneifolia Gópp., P. ettingshauseni Mass., P. 
gracilis Ett, P. grandifolia Ung. P. aynhauseniana Göpp., P. 
pannonica Ett, P. rugosa Göpp., P. sterculiefolia Ett, Acer 
Reifolium (Viv.) Brongn., A. heerii Mass., A. heerü deperditum 
Mass, A. heeri ficifolium Mass, A. heerü productum Mass., 
Acer heerü tricuspidatum Mass., A. heerü trilobatum Mass., A. 
