50 BOTANICAL GAZETTE TJULY 



In reply to the question whether each one of the described 

 species of Liriodendron represents a definite species established 

 in nature, we are compelled to answer in the negative ; for the 

 evidence that the majority of these forms were distinct species, in 

 any proper sense, is entirely insufficient. At the same time, we 

 are led to believe, from a study of these fossil forms in conjunc- 

 tion with the modern form and its varieties, that Liriodendron in 

 the course of its evolution has passed through a series of parallel 

 stages, as we will endeavor to show. It matters little whether 

 we call these stages species or stages. 



The purpose of Holm's^° paper on Liriodendron is stated as 

 follows: **The object of these notes .... is to prove that, as 

 far as is known to the writer, there is not a greater difference 

 in the foliage between many of the extinct species of Lirioden- 

 dron than between a series of leaves from a very young tree or 

 from a branch of an older one of our living Z. Tulipifera ;'' and 

 he then proceeds to attack the validity of the various species. 

 Since 1890 a host of specimens, including many interesting 

 forms," have come to light, and much new material has been 

 published. Two works in particular may be mentioned, the last 

 labors of the pioneers Lesquereux" and Newberry ^^ being issued 

 posthumously, as well as various contributions from Hollick and 

 others on the plant remains from Long and Staten islands and 

 elsewhere. The time seems opportune for recording some 

 additional notes, and correcting several current inaccuracies. 

 It is far from the purpose to attempt to diminish or increase 



"Proc. U. S. Nat. Mus. 13: 16. 1890. 



"The following new species : Liriodendrppsis angustifolia Newb., L c, p. 84 5 

 Liriodendron alatum Newb., Hollick in Bull Terr. Bot. Club 21 : 467. 1894 ; L^ acu- 

 minatum hilobafum Lesq., /. r., p. 207 ; L.Snoiuii Lesq., /. r., p. 209 ; Z. succedens 

 Dawson, Trans. Roy. Soc. Canada n : 62,//. 8. fig. 36. 1893 (1894) ; L,, praetiiHpiMum 

 Dawson, I. cfig. 27/ and the winged petiole forms of Liriophyllum populoides Lesq.» 

 ' Hollick, /. €, ' 



h 



"Flora of Dakota group, edited by F. H. Knowllon. Monograph 17 U. S. Geol. 

 Surv. 1 89 1. 



^3 Flora of the Amboy clays, edited by Arthur Hollick, Monograph 26 U.S. 

 Geol. Surv. 1895, 



