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A TEXTBOOK OF THEORETICAL BOTANY 



away at maturity. The presence of an axial core is shown not only by the 

 vasculation in some cases, but in the above species by the fact that in the 

 male flowers an axial column rises in the centre of the flower, though no 

 carpels are formed on it. In Osyris alba (Santalaceae) there is only one 

 placental bundle, but it is formed by the fusion of the three median, ventral 

 carpel traces, which is fairly good evidence that the carpels do take part in 

 forming the free placenta, with or without an axial core, and that the carpels 

 are of the peltate type. 



The style is a columnar structure arising from the ovary and bearing 

 the stigma, which is a secretory area on which pollen grains are deposited 

 and where they germinate (Fig. 1 189). Although the stigma has a distinctive 

 name, it is not always a distinct organ and cannot be properly considered 

 apart from the style, of which it may be only a specialized area, or, in the 

 absence of a style, an area of the ovary wall itself. 



The style is the product of intercalary growth and is therefore a secon- 



FiG. 1 1 89. — A selection of various tvpes of stigmas. (1) Celtis. {2) Empetnmi. 

 (3) Burmannia. (4) Hura. (5) Begonia. (6) Jfuglans. (7) Viola. (8) Nuphar. 

 (9) Opuntia. {From Le Maout and Decaisne.) 



