METAMORPHOSES OF INFLORESCENCES AND FLOWERS. 



93 



METAMORPHOSES OF INFLORESCENCES AND FLOWERS. 

 By Rev. Prof. G. Henslow, M.A., V.M.H. 



Introduction. — One of the most inexplicable things in plant-life is what 

 may be called a normally localised energy concerned in making some one 

 organ, taking up the function of another, so that a special structure is 

 evolved, of a different kind, and altogether outside its usually perfectly 

 limited sphere of action. 



Hence, assuming that a whole inflorescence contains a peduncle and 

 pedicels, bracts and bracteoles, the flowers being composed of sepals, petals, 

 stamens, and carpels, all sorts of interchanges, very often only imperfectly 

 effected, may occur between them. 



If it be asked why any particular metamorphosis takes place, scarcely 

 any satisfactory answer can yet be given at all. The reason is that it is 

 a matter which is concerned with or executed by life ; and we do not know 

 what life is, nor the laws governing its activities. We see the effects of 

 unknown causes in the changes of structures, but we know nothing of 

 the nature of those causes and processes executed by life, which have 

 brought them about. We may, however, always see an object in view, 

 whether it be successfully obtained or not ; but how it came about, for 

 example, that the peduncle and pedicels of the inflorescence of the Vine 

 could be converted into an excellent climbing organ or tendril, as perfectly 

 adapted to its purpose as the stalk and branchlets are to carry grapes, is 

 a mystery past finding out. 



If a Vine be well searched, many examples can be found in which 

 the tendril bears a few abortive buds revealing its true source. 



We must, however, distinguish between useful metamorphoses on the 

 one hand, and more or less useless ones on the other. The former have 

 resulted in well-defined and important organs. The latter remain as 

 abortive attempts at changes only. 



Metamorphoses in Peduncles and Pedicels. 



Useful Changes. — Besides the Vine, there are other plants of which 

 the flowering branch has been changed into tendrils, but of different 

 kinds. Ampelopsis hederacea or Virginia Creeper and its ally A. Vettchii, 

 the Passion-flower and Bauhinia, well illustrate Nature's power of adapta- 

 tion of floral axes for climbing by tendrils, in different ways and in different 

 families of plants. 



Everybody is familiar with the method of climbing by adhesive pads 

 in the two species of Ampelopsis, both belonging to the Vine family. 



The Virginia Creeper turns its tendrils away from the light so a 

 reach, if possible, a rough surface. As soon as the hooks at the ends of 

 the branchlets catch in any little depression, the irritation causes them to 

 swell into adhesive pads, which are never formed previously to coin.- t. 



In the Japanese species, however, the pads are developed < 



