1914] BAILEY &* SINNOTT—PHYLOGENY OF ANGIOSPERMS 57 



" AGGREGATE 1 ' RAYS STAGES IN THE REDUCTION AND DISINTEGRA- 

 TION OF WIDE MULTISERIATE RAYS 



In the Fagales and Casuarinaceae there is a very complete 

 series of form in which the progressive reduction and disintegra- 

 tion of wide multiseriate rays can be traced in detail. During this 

 process of reduction the wide rays appear usually at later and later 

 stages in ontogeny, until they finally disappear. The so-called 

 aggregate" rays are stages in the disintegration of wide multi- 

 seriate rays. Stimulating types of growth and injury recall the 

 wide rays in regions where they have been lost, and are frequently 

 most effective in those regions which are supposed to be conserva- 

 tive, such as the first annual ring, root, node, and seedling. Stunted, 

 suppressed, poorly nourished types of growth, and severe distorting 

 injuries hasten the reduction and disintegration of the wide multi- 

 seriate rays. In this process of reduction vestiges of the wide 



rays tend to be more persistent in the peduncle, root, and nodal 

 regions. 



IDEXED 



The multiseriate ray does not appear to be of recent origin, since 

 it is well developed in most tropical and temperate families and 

 extends through the Tertiary at least to the Middle Cretaceous. 

 This type of ray structure originated in all probability by the 

 gradual increase in width of the primitive uniseriate raw 



PHYLOGENY OF THE AMEN'TIFERAE 



One character, of course, cannot be considered conclusive evi- 

 dence for assuming that a plant or group of plants is "regressive" 

 or reduced, since all characters will not be similarly affected by 

 changes in the environment or physiological activity, but the reduc- 

 tion of wide rays in the Fagales indicates that this order, as well as 

 the Casuarinaceae, has been subjected to a strong modifying influ- 

 ence. This fact, taken together with the occurrence of syncarpy, 

 epigyny, abortive ovules, and vestiges of bisexual flowers and 

 floral envelopes, emphasizes the importance of the frequently 



repeated suggestion that the Amentiferae. instead of being the 

 m ost primitive of angiosperms, are a group of specialized families 



