AMERICAN 
JOURNAL OF BOTANY 
Vol. I November, 1914 No. 9 
INVESTIGATIONS ON THE PHYLOGENY OF THE 
ANGIOSPERMS 
3. Nodal Anatomy and the Morphology of Stipules 
Edmund W. Sinnott and Irving W. Bailey 
The morphology of stipules has been a much debated subject 
since careful study of plant structures began. These generally small 
and inconspicuous appendages at the base of the petiole, which occur 
so constantly in some families of angiosperms and which are so in- 
variably absent in others, have been regarded variously as "accessory 
leaves," as independent organs, as a "product of the leaf base of the 
primordial leaf," as the remains of the two lateral leaflets of a three- 
compound leaf, as an incomplete axillary ligule, as a reduced leaf- 
sheath or as the remains of such a sheath of fused leaves as occurs in 
Equisetum. Almost everyone who has written on the subject has 
had a different idea as to just what the nature of stipules is and what 
has been the cause of their origin ; and the relations between stipules, 
leaf-sheath, ligule, tendril, petiolar spine and ochrea have been widely 
discussed by many botanists. The following paper has as its object 
a presentation of certain anatomical facts, apparently overlooked 
hitherto, which seem to be of importance in connection with this 
general problem. 
One of the writers (3) has recently made a comparative study 
of the anatomy of the node throughout the angiosperms and has 
come to certain conclusions as to the evolutionary development of the 
various types of nodal structure in that group. The facts and con- 
clusions in his paper may be briefly summarized as follows. 
[The Journal for October (i: 357-440) was issued 31 Oct. 1914.] 
441 
