CHAPTER II 



ANTHOLOGY: THE GENERAL NATURE OF THE FLOWER 



The Phytomer. — In order to accurately understand the structure of 

 the flower, we must first consider the general characters of its struc- 

 tural units, which are the same as those of the stem upon which it 

 is borne and of which it is a part. These are well displayed in a 

 willow twig (Fig. 1), presenting a main stem, with perhaps short 

 branches below and leaves above. These leaves are found, upon exami- 

 nation, to arise at regularly occurring points, thus dividing the stem 

 into parts which are seen to possess definite and uniform characteristics. 

 In common language these parts are called "joints," and technically, 

 Phytomers or Phytons. 



Units of Structure. — The upper portion of each phyton is commonly 

 somewhat enlarged and it possesses the power of giving rise to three new 

 structures: (1) the leaf (a), or in many plants a circle of two or more 

 leaves; (2) a superimposed phytomer, continuing the growth of the 

 stem in its original direction; (3) a branch extending the growth of 

 the stem in a lateral direction, or, if there be more than one leaf, then 

 a corresponding number of such branches. Upon the upper portion of 

 the stem the branches are seen still undeveloped, and in the form of 

 buds (b). The bud originates, with rare exceptions, at the point where 

 the leaf emerges from the stem and upon its upper side. This point is 

 known as the Leaf-axil. The portion of the phytomer which gives 

 origin to these three structures is called its Node (c). The portion 

 intervening between two nodes is called the Internode (d). The inter- 

 node does not normally possess the power of giving origin to these 

 new parts. 



The branch is found, after development, not to differ essentially 

 from the stem, so that a branch may be regarded as a lateral stem, 

 secondary, tertiary, and so on. In noting hereafter the development of 

 the other parts of the plant out of those here named, we shall frequently 

 find the latter so modified that we shall be unable to recognize them 

 by the ordinary methods of examination, so that the relative positions 

 which they occupy will prove an important guide. A correct under- 



