1909] Seedlings of Ph^nogamous Plants. 243 



Tilia, etc., the leaves possess petioles and blades, but frequently 

 of an outline very distinct from that of the final leaves. In 

 Liriodendron for instance, the earliest leaves are very different 

 from those of the mature tree; they are roundish to obovate, oi 

 even obcordate, and in the mature tree this simple type of leaf 

 occurs only at the very apex or base of the branches. The study 

 of this, frequently very striking, variation in foliage affords much 

 of interest, not only from a morphological point of view, but also, 

 and quite especially, because many of these seedling-leaves may 

 be looked upon as still representing the foliage of ancestral 

 types. 



In the present paper I wished only to call attention to 

 some of the most salient points observable in the seedlings, so 

 far as concerns the external structure of their organs, and it is 

 readily to be seen that even if the nvmiber of types is not very 

 large, these seedlings nevertheless illustrate several interesting 

 characteristics, indicating to some extent the future growth of 

 the species. The study of mature rhizomes is often very 

 difficult, when the seedling stage is not known ; for instance, when 

 the reproduction depends upon the cotyledonary buds; when the 

 hypocotyl or the primary root, or both, actually become the 

 first visible indication of the rhizome in its many, and highly- 

 differentiated modifications. It is, therefore, necessary to study 

 our plants from this point of view, and I hope the few tvpes 

 which I have described may prove helpful in this respect. The 

 literature upon the subject is very extensive, but there are some 

 works in which very complete lists of papers have been compiled, 

 and among these may be mentioned: Beitrage zur Morphologie 

 und Biologic der Keimung by Klebs (1), and, A theory of the 

 origin of Monocotyledons by Miss Sargant (2). In regard to the 

 Grass-embryo there is a very comprehensive paper by Aug. 

 Schlickum : Morphologischer und anatomischer Vergleich der 

 Kotyledonen und ersten Laubblatter der Keimpflanzen der 

 Monokotylen (3), in which the reader will find a well drawn 

 comparison between the various theories that have been express- 

 ed in regard to this very complicated structure. 



(1). Untersuch. Bot. IiLstitut, Tubingen, 1881-1885, p. 536. 



(2). Ann. of Botany, Vol. 17, 1903, p. 1. 



(3). Bibliotheca Botanica Stuttgart, 1896. 



See also: B. JOnsson in Lund's Univ. Arsskr. Vol. 38, 1902; Arthur 

 W. Hill in Ann. of Bot. Vol. 19 and 21, 1905-1907, and Sir John Lubbock, 

 Contributions to the knowledge of seedlings, 1892. 



