ORGANS OF REPRODUCTION INFLORESCENCE. 



105 



duce the plant. Still such instances must be regarded as exceptional and irregular ; 

 and hence the buds so formed are termed adventitious. 



ORGANS OF REPRODUCTION. 



The foregoing descriptions have referred to those parts of a plant which are con- 

 cerned in maintaining its own vitality and increasing its development, and may 

 therefore be termed personal ; but there are other parts which have for their functions 

 the production of new individuals, and may thence be called relative. Such are the 

 organs of fructification, and they are known generally as flowers, seeds, and fruit. We 

 shall consider these in their order. 



The Flower is in part a reproductive organ, with certain protective coverings. It 

 consists of various parts, as the bract, calyx, corolla, stamens, and pistils, in their order, 

 proceeding from without inwards. 



The Inflorescence. A number of terms have been devised to enable us readily 

 to designate the appearance which the whole arrangement of flowers presents upon the 

 flower stalk, and it will be convenient to place them here before we enter upon the 

 consideration of the parts of each flower. Such an arrangement of flowers is commonly 

 termed the inflorescence. 



The flowers are immediately supported upon the stem in one of two ways ; either 

 by a more or less elongated branch, or foot stalk, termed the peduncle, or by a flattened 

 more or less fleshy organ, as in the Strawberry, known as the receptacle. The peduncle 

 differs in no essential respect from the foot stalk of a leaf, its variation being merely 

 that of size and form to enable it to support the flowers. When it supplies the place 

 of a stem, as in the Cowslip (Primula], it is called a scape ; and when it is elongated, 

 and passes in a straight line throughout the inflorescence, it is called an axis, or rachis, 

 as in Grasses, Fig. 184 a. In many instances, as in the Vmbelliferce (the Parsley), it 

 is divided into a number of lesser peduncles, each one still supporting many little 

 flowers, and the divisions are termed pedicels. 



The receptacle is very commonly met with, and more particularly 

 in the most numerous class of plants, the Compositae ; but it is there 

 not fleshy, and is sometimes distinguished from the fleshy receptacle 

 of such plants as the Strawberry by the term thalamus. The juicy 

 part of the Strawberry is the receptacle, as may be observed by 

 noticing the position of the little seeds which are placed upon its 

 outer surface. The recep- 

 tacle is the terminal grow- 

 ing point of the stem, 

 and is closely analogous 

 to the flower head of the 

 Arum, Fig. 192. 



The arrangement of the 

 flowers upon the foot stalk 

 or receptacle is primarily 



divisible into two classes Fig. 189. The Catkins of the Willow, shoeing 

 viz.. such as have n a multitude of flowers sessile upon a common 



' rachis. 

 other intervening foot 



stalk, and then are called sessile or setting, and such as are stalked. The examples of 

 sessile inflorescence are the Spike, Locusta, Spadix, Catkin, Capitulum, and Gflomerulu> 



Fig. 190.-The 

 Spike. 



