16 lp:aves of liriodendron — holm. 



entitled " The Ancestors of the Tulip-tree,"* and to several other pai)ers 

 important lo this study. 



If we wished to find a complete account of the variation of the leaves 

 of Liriodendron Tulipifera, should we not seek it in a paper in which the 

 author attempted to show its ancestral conditions! But I was disap 

 pointed in reading this paper, for, curiously enough, Dr. Newberry doety 

 not pay any considerable attention to the recent species. He enumer- 

 ates and figures some new fossil species, and mentions, though briefly, 

 some other ones described before, but the comparison with the Jiving 

 tree which I was looking for was entirely wanting. On turning to some 

 other authors, for instance, Heer, Lesquereux, Saporta and others, I 

 found descriptions and figures of fossil Liriodendron leaves, and I shall 

 now try to give a comparison of these ancient types with the only living 

 species, Liriodendron TaJipifera L. 



The object of these notes, as will appear later, is to prove that, as far 

 as is known to the author, there is not a greater difference in the foli- 

 age between many of the extinct species of Liriodendron than between a 

 series of leaves from a very joung rree or from a branch of an older one 

 of our recent species. I shall therefore* take as a point for discussion 

 the last sentence in Dr. Newberry's paper: "Hence, until more ma- 

 terial shall show the simple, ovate, or lanceolate forms to be connected 

 by insensible gradations with others, I must regard them as specifically 

 distinct." 



The most rational manner of treating the question of the differ- 

 ence between the fossil and the recent species is to commence the ex- 

 amination with the living plant, of which the most complete material 

 will be always at hand and certainly give the most reliable result. We 

 have then to look at the descriptions given by the different authors in 

 the systematic works. The species, as well as the genus, was first de- 

 scribed by Linne in his " Species plantarum," 1764, p. 755, where he 

 described the leaf as " tripartito aceris folio, media lacinia velut ab- 

 scissa." It seems now, however, as if there is some disagreement 

 among authors, who have either considered the leaf as three-lobed, with 

 the middle lobe notched at its summit, or as a regular four-lobed leaf, 

 but with the apex cut off. We shall see that of seventeen authors 

 eight have described it as three-lobed, while the remaining nine have 

 called it four-lobed. The different diagnoses of the leaf are as follows : 

 "Foliis trilobis truncatis" Willdenow;t "leaves three-lobed, with the 

 central lobe truncated" Nuttall ; | " leaves truncate at the end, with two 

 side lobes" Eaton ;§ "leaves divided into three lobes, of which the 

 middle one is horizontally notched at its summit and the two lower 

 ones rounded at the base" Browne ;|| " leaves dilated, rounded or sub- 



* Bulletin of the Torrey Botau. Club, vol. xiv, No. 1, 1887. 

 tWilldenow: Species plantarum, vol. ii. Pars II, p. 1*254. 

 tThs. Nuttall: Genera of North Americau plauts, 1818, p. 18. 

 § A. Eaton : Manual of Botany for North America, 1833, p. 208. 

 II D. I. Browne : The trees of America, 1846, p. ^5. 



