On the Structure of the Leaf in Cretaceous Pines . 1 
BY 
EDWARD C. JEFFREY 
Professor of Plant Morphology in Harvard University. 
With Plates XIII and XIV. 
'"'HE leaf in the Gymnosperms has been the subject of many investiga- 
X tions, and it is now recognized that the fibrovascular structures of 
the foliar organs in this group are phylogenetically important. It is the 
purpose of the present communication to call attention to certain structural 
features of the leaves in Cretaceous Pines and allied forms, which appear to 
have an important bearing on the much disputed problem of the origin of 
the Coniferales. 
It will be appropriate to commence this record with the description of 
those pine-like leaf remains which appear to present the most primitive 
characters. Fig. i, PI. XIII, shows a magnified external view of a short- 
shoot or brachyblast of an Abietineous species, which is rather rare in the 
Kreischerville deposits, from which all the material described in the present 
connexion has been derived. It will be noticed at once that it differs 
so strikingly from the fascicular shoots of any living species of Pinus , that, 
judging from external features alone, it might well be doubted whether 
our specimen was a short-shoot at all. The specimen represented in 
Fig. i, PI. XIII, shows at the base scars of fallen leaves which in this case 
are not foliage leaves, but are of the nature of bracts. Above the denuded 
region is a number of bracts still in situ. At the very top of the figure 
the brachyblast presents a truncated appearance and is crowned by the 
broken bases of a number of true foliage leaves. Fig. 3, PI. XIII, shows 
another short-shoot of this species, which is in a much better condition 
1 Contributions from the Phanerogamic Laboratories of Harvard University, No. 10. 
[Annals of Botany, Vol. XXII. No. LXXXVI. April, 1908.] 
