The Nature and Origin of Stipules. 19 



stipules, the stipules of Ficus elastica Roxh. and Magnolia grandi- 

 jlora L. as axillar}'' ligules. 



■Ward, L. F. — The Paleontologic History of the Genus Platanus. Proc. 

 U.'S. Nat. Mus. 11: 39-42. 1888. 



Professor Ward sa^^s (p. 41 ) in speaking of the fossil leaves of 

 Platanus basilobata Ward, of the Yellowstone valley, that some 

 of those found had " a remarkable expansion at the base of the 

 blade, projecting backward on the leaf-stalk and having two to 

 five lobes or points. 



'' These expansions are to be interpreted as evidence that the 

 leaves all belong to Platanus or to some extinct ancestral type of 

 the genus, since something quite analagous to them is found in 

 our American plane-tree. The ordinar}^ leaves of this tree are, 

 it is true, destitirte of basilar expansions, but those on young 

 shoots, and sometimes those on the lower or non-fruit-bearing 

 branches of trees exhibit this peculiarity. 



" In place of this backward expansion of the blade many syca- 

 more leaves have an appendage similar in shape at the base of the 

 leaf-stalk, as though the once basilar appendage had been sep- 

 arated from the blade and crowded down the petiole to its point 

 of insertion." This is shown in a short-petioled, wedge-shaped 

 leaf from a 3'oung shoot of Platanus corresponding to the fossil 

 form of Platanus appendiculata Lesq. from the auriferous gravels 

 of California. The indication is that " the constriction seen in 

 the fossil forms between the blade of the leaf and the appendage 

 would seem to represent the beginning of this process of detach- 

 ment." 



If'ard, L. F.— Origin of the Plane-Trees. Am. Nat. 24: 797-810. 1890. 



The same cases as those in the preceding paper are discussed, 

 the appendages in Platanus appendiculata Lesq. being described as 

 stipular, while those of P. nobilis Newb. and P. basilobata Ward 

 are not so considered. 



Lubbock, Sir Jolin.— On Stipules, their Form and Function. Jour. 

 Linn. Soc. Lond. 28: 217-243. 1890. 



" The primary function of stipules seems to be to protect the 

 bud. In other species, however, they serve as accessory or deputy 

 leaves. Their protective function is confirmed by the fact of 

 their early fall. Some are more persistent than the leaves and 

 protect the leaves of the following year. 



