THE STAMEN 153 



can often be determined only by the number and position of the major 

 vascular bundles. 



Nectaries are present in many places in the flower, on all the floral 

 appendages and, frequently, on the receptacle. No structural nectary 

 occurs in the primitive flowers of many woody Ranales. Their absence 

 in "simple" flowers, such as those of the Amentiferae, has been con- 

 sidered support for the view that anemophily is the primitive method 

 of pollination. But these flowers are obviously greatly reduced, and lack 

 of nectaries may represent loss of these structures. The general story of 

 development of nectaries can be seen in living forms. Where pollination 

 is by beetles exclusively, or nearly so — Eupomatia, CaJijcanthus — there 

 are no nectaries; the insects feed on nonsecretory "food bodies" (Fig. 

 69). (Superficially and in cell content, these food bodies may resemble 

 nectaries.) In the Magnoliaceae {Magnolia, Talauma), nectar is secreted, 

 but not in localized areas; it is described as diffused through petal 

 cuticles and excreted through enlarged stomata on petal bases and 

 carpel surfaces. The entire flower of Magnolia has been called a nectary. 

 In some of the Nymphaeaceae, a primitive family, nectar is reported 

 secreted by the perianth. Since a small amount of nectar has been 

 reported in one species of Magnolia and one species of Calijcanthus, 

 genera which have food bodies and beetle pollination, nectar secretion 

 apparently originated while the food-body method existed. 



It has been suggested that, in the evolution of the flower, a pro- 

 gressive change has occurred in nectary position, from the base of the 

 flower and the receptacle inward and upward on the appendages. In 

 primitive dicotyledons, nectaries occur on the perianth and on the 

 outer parts of the receptacle; in the higher families, they occur chiefly 

 on the sporophylls or on the "receptacle" (fused perianth and sporo- 

 phylls) around and above the ovary. In the monocotyledons, the nec- 

 taries are on the perianth, stamens, and especially the carpels (septal 

 nectaries). Differences in the morphological nature of the nectaries 

 seem not to have been considered in this view of a phylogenetic 

 change in nectary position, but a general change is evident. Change in 

 nectary position necessarily accompanies fusion of appendages, and, in 

 advanced floral types, nectaries are present higher up in the flower. 



The location of nectaries that represent reduced floral appendages 

 may be of much importance in the determination of phylogenetic rela- 

 tionships. For example, the nectariferous disc of some genera of the 

 Proteaceae (four separate organs in other genera) is, from the evidence 

 of comparative form and anatomy, a vestigial corolla, and this family 

 can no longer be placed in the supposedly primitive Apetalae. The nec- 

 taries of the Salicaceae, which are reduced perianth parts, demonstrate 

 that the flowers of this family are not primitively simple. 



