1914] BAILEY fir SINNOTT—PHYLOGENY OF ANGIOSPERMS 43 



in these species is well illustrated by the peduncles of Quercus 

 coccinea Moench. and Q. ilicifolia Wang. Multiseriate rays are 

 formed by the first activity of the cambium and show no putative 



* 



stages of "aggregation" and "fusion" in their ontogenetic devel- 

 opment (fig. 15). Conditions equally significant have been 

 observed by the writers in the peduncles of Casuarina suberosa 

 Otto and Dietr., a species which possesses well developed "aggre- 

 gate" rays in the seedling stem (fig. 7). The peduncles of Quercus 

 pedunculated Ehrh., Alnus maritima (Marsh) MuhL, A. incana L. 

 Moench. , and A. yasha Matsum, are slender and possess narrower 

 zones of secondary tissue. However , even in these peduncles 

 biseriate and triseriate as well as uniseriate rays are often formed 

 by the first activity of the cambium. 



THE NODE 



Scott, Jeffrey, and others have emphasized the conservatism 

 of the leaf trace and neighboring tissues. The structure of the 



jm 



development of "aggregate" and "compound" rays. 



Throughout the Fagales there is a marked tendency for large 

 rays to be more strongly developed in the young shoot in the 

 vicinity of those strands of the vascular cylinder which are about 

 to pass out to the leaves. These rays are in many cases composed 

 of homogeneous ray parenchyma, whereas the wide rays in other 

 radii of the stem arise apparently by a "compounding" process 

 from congeries of uniseriate rays. Perhaps the most significant con- 

 ditions are those which occur in supposedly primitive representa- 

 tives of the Fagales. Among the Betulaceae, for example, vestiges 

 of "aggregate" rays may occur in the nodal region when the inter- 

 nodes possess only uniseriate rays (fig. 12). Similar conditions are 

 of frequent occurrence in the white oaks (subgenus Lepidobalanus). 

 Stems of Quercus alba L. often possess for many years only uni- 

 seriate rays except in the vicinity of the lateral traces of the 

 leaves (fig. 10). The root may likewise be devoid of wide sheets 

 of ray tissue except in the vicinity of the vascular elements which 

 pass out to the rootlets (figs. 6, 1 1, and 20). In this region vestiges 

 of wide sheets of homogeneous rav parenchyma occur. Especially 



