1094 A TEXTBOOK OF THEORETICAL BOTANY 



Adhesion occasionally affects the perianth members, the calyx and 

 corolla being united, while the androecium may in some cases be united to 

 the gynoecium. There are also certain rare instances where an inferior 

 gynoecium is adherent to the vegetative axis or to the pedicels of neigh- 

 bouring flowers (Pig. 1062), but the commonest example of adhesion is the 

 union of staminal filaments more or less completely to the corolla. This 



Fig. 1062. — Petaguia sanicidifolia. Lateral flowers adherent to the 

 inferior ovaries of the terminal flowers. {After Baillon.) 



arises from a congenital union of the two sets of primordia in the flower bud, 

 so that for some time they appear to develop as unit structures. Separation 

 may be so far postponed that only the anthers and the tips of the petals 

 are free. The general term for such a congenital fusion of dissimilar 

 organs is adnation, and the special, though incorrect, term applied to 

 the stamens in this case is epipetalous, which should imply that the stamens 

 are developed on the petals, but this, as we have seen, is not the case. 

 Indeed, if, as is not uncommon, the stamens develop more rapidly than 

 the petals, the latter may appear to arise on the stamens {e.g., Primula), 

 though this is only an appearance due to the different rates of development 

 in the united rudiments.* Owing to the prevalence of strict alternation 

 of parts in the flower, adnate stamens are generally found in sympetalous 



* The parallel case, of episepalous stamens, is rare, but it occurs in Banksia and other 

 members of the Proteaceae. 



